Friday, September 19, 2014

Fruit-eating Birds

Cedar Waxwing

The Duluth-Superior area is so well known for our hawk migration and the amazing appearance of jaegers along Wisconsin Point every fall that we don’t pay enough attention to other cool birds passing through. Right now the most exciting birds in my own neighborhood have been the hordes of waxwings and thrushes descending on mountain ash trees and other fruit-bearing trees and shrubs. Up at Hawk Ridge, we can watch waxwing flocks numbering two or three to up to 40 or 50 passing through. Waxwings are shaped a bit like starlings, with triangular pointed wings, but are smaller and weigh less than half of what starlings weigh. That extra mass makes starlings powerhouses in flight, as you can see if you’ve ever seen a huge flock of them wheeling about in the sky—those YouTube videos showing enormous bird flocks forming bizarre shapes are starlings. Cedar Waxwings fly in a far more delicate, buoyant way. Their flocks seem to move in a much more leisurely fashion, and the way each bird shifts position relative to the others makes the flock appear to be gently swirling through the sky.

Lovely as flying waxwings are, I love being where they set down for a spell in convivial feeding groups. Of course, there are degrees of conviviality. There can be 20 or 30 Cedar Waxwings in a single mountain ash, but seldom will there be more than 2, and usually just one, per cluster of berries. I don’t think I’ve ever seen waxwings pass berries to one another in fall—their mission seems entirely about devouring as many as they can, laying on fat deposits that will help them over days of scarcity come winter.

Cedar Waxwing

This week I’ve been hearing waxwings wherever I go in my neighborhood or up at Hawk Ridge, and Thursday I spent a little time in my yard and my neighbor’s taking photos. The flock I spent time with included a lot of young birds, which have streaked breasts and a somewhat shaggier crest than adults.

American Robin

Swainson's Thrush

The waxwings are in the company of thrushes as well. Most are American Robins, but a good number of Swainson’s Thrushes have also been hanging out this week. The thrushes seem rather meek and mild—when I’ve watched a waxwing fly to a branch near a Swainson’s Thrush, the thrush always flew off to another branch. The American Robins are the bullies of the crowd—several times I’ve watched one fly straight toward a waxwing or Swainson’s Thrush at high speed. Instantly the smaller bird flies off, leaving a good bunch of berries to the robin.

Even though virtually all the birds in these trees right now have been Cedar Waxwings, Swainson’s Thrushes, and robins, I keep looking through all the branches in hopes of an outlier—a Red-eyed Vireo is often flitting about in the same trees, presumably eating a berry or two to sweeten its usual buggy fare. Nashville Warblers and American Redstarts were among them there earlier in the week, but they seem to have left with the drop in temperatures. The one time I had a Townsend’s Solitaire in my yard was during fall migration, mixed in with a flock of robins and waxwings. Hope springs eternal.

With or without outliers, watching and photographing just the common species has been delightful. September is one of the months that could use an extra week or two, just to pack in all the wonderful bird activity. But it always ends after 30 days, just as the berry supplies inevitably dwindle—in just a couple of days, the birds almost completely stripped my favorite mountain ash of its berries. Just as the birds are grabbing for all the berries they can, while September is here, we’ve got to grab for all the gusto we can.

Swainson's Thrush

Thursday, September 18, 2014

Hawk Ridge Update

Check out the events for this year's Hawk Ridge Weekend. I'll be speaking about all the fun I had on my Conservation Big Year on Friday night, and leading a boat tour of the St. Louis River on Saturday morning.
Broad-winged Hawk
Roosting Broad-winged Hawk

On September 15 and 16, 2014, I was behind on several projects and was stuck at home. But northwest winds, clear skies, and something deep in my bones kept telling me things would be hopping at Hawk Ridge. I live in the neighborhood right below the ridge, but often miss seeing many raptors on the big flight days, though I can usually tell a day is good by the songbird activity in my yard.

White-throated Sparrow
White-throated Sparrow

Monday, birds were really moving about. I couldn’t spend too much time looking out the window, but did spot a Black-and-white Warbler, a couple of American Redstarts, and a Palm Warbler in addition to a dozen or so White-throated Sparrows. I didn’t need to look out to be aware of lots of Blue Jays—their squawking not only told me they were around but that one or two Sharp-shinned Hawks were cruising down Peabody Street.
I checked the count via the website at that night, and 6,622 hawks had gone by—the biggest day so far this season. As usual when the count is so large, the vast majority of the birds—over 5,500—were Broad-winged Hawks.

When we have a big day like that, the following morning is often quite good, too. That’s because the birds coursing through at the end of a big day have to land somewhere for the night, so are usually seen taking off the next morning. Back in the 90s, the morning after a September day when the count was over 20,000, I got phone calls from three different kids working at supermarkets, telling me about the huge numbers of hawks circling over the parking lots. Dark pavement is first to warm up as the sun climbs in the morning sky, so the first useful thermals of the day often develop over parking lots and highways. On the biggest days of all, hawk numbers are highest at midday, but so is their flight. You’ll see fewer birds but they’ll be closer during early and mid morning.

Tuesday held to that pattern. Mike Furtman posted beautiful photos he took Tuesday morning on facebook. But powerful winds kept the numbers lower—those winds break up the thermals. By day’s end, the total was 801, with the Broad-wing count at 329—an order of magnitude lower than Monday, but darned respectable.

Young Broad-winged Hawk flying over Hawk Ridge
Soaring immature Broad-winged Hawk

Wednesday started out with light winds from the southwest. When I woke about 6:15, I spotted a thrush outside my window in the semi-darkness, and a few minutes later, the first bird I spotted from my office window was a hummingbird. I couldn’t get away immediately, but headed up to Hawk Ridge at 10 am for a couple of hours. The counters were busy tallying small kettles of Broad-wings and flocks of Blue Jays and the occasional small flock of Pine Siskins, and I got busy photographing a Lapland Longspur who showed up at the main overlook and stuck around the same spot for a long time while people took pictures. Unfortunately, the last photos I’d taken were in a dark setting and I had my ISO set to 2500, but the bird was so cooperative in such perfect light that the pictures turned out not too bad.

Lapland Longspur
Lapland Longspur at Hawk Ridge!

The wind shifted to the east and the temperature dropped dramatically right about at noon when I had to leave anyway. I’d had a great day, and the final count ended up being 2,941, with the Broad-wing total at 2,451—less than half of Monday’s numbers, but thrilling nonetheless.

Anything can happen in mid-September—sometimes we have single-day counts well into 5 digits, but it’s always hard to predict. Our current Broad-wing total for the season is now over 16,000. This weekend is Hawk Ridge Weekend, and the weather may not be ideal, but when the winds shift to the northwest again, we could get a humongous day. Or not. Whatever happens, birding up at Hawk Ridge in September is like a box of chocolates. You never know what you’re going to get, but it’s certain to be sweet.

Lapland Longspur
Lapland Longspur casting an eye to the sky. Looking for hawks?

Monday, September 15, 2014

Book review: The Warbler Guide

Last summer, the Princeton University Press released a book by Tom Stephenson and Scott Whittle, The Warbler Guide. When I first read about it, I admit I rolled my eyes thinking, “Not another one!” My library already included four field guides specifically about warblers. They’re all good in one way or another, but I don’t usually consider field guides to families to be useful, especially for beginners, because they don’t show similar but unrelated birds that can be confusing. (The great comprehensive guides to families are a different story.) The Peterson guide to warblers is wonderfully comprehensive, but even that one is worthless in the field when someone is starting out and isn’t sure whether a particular bird is a flycatcher, vireo, kinglet, or warbler. But it’s very true that birders of all levels are drawn to warblers, and anything that makes identifying them easier is a Good Thing, and the publishers sent me a free copy, so I opened it. And WHOA! The Warbler Guide is a game changer.

The 137-page section that starts the book is a brilliant tutorial in the basics of warbler identification—both by sight and sound—using a methodical, objective approach that would benefit anyone studying any group of birds. It so thoroughly covers identification both by appearance and vocalizations that I want to highlight the two sections separately.

Warbler Appearance

In their “Topographic Tour,” Stephenson and Whittle use brilliant colors to outline different feather groups and body parts within a nice color photo, rather than using a simple line to point out the general area of what could be a large or small structure not so easy for beginners to figure out. David Sibley in his Birding Basics used black-and-white line drawings, and Kenn Kaufman in his Advanced Guide to Birding brought it to the next level with black and white outlines next to actual photos to show the particular feather groups and body parts, but Stephenson and Whittle bring this clear-minded approach to the next level.

The 40-page section on things to pay attention to when looking at warblers is rich in photos showing each feature on different species and, where pertinent, on similar non-warblers. Bill shape and length, eye rings, eye lines, length of the tail and how relatively long or short the undertail coverts are—all these features and more are thoroughly covered, and reading this section will make anyone more able to discern a bird’s important features. The section is rich with photos clearly comparing and contrasting each feature on different warblers and non-warblers. There is also a section on aging and sexing warblers—and the authors show how this is fairly straightforward with some species but virtually or completely impossible with others. They use wonderful drawings by Catherine Hamilton to illustrate points more clearly understood and compared with drawings than photos.

There are also nine two-page spreads called visual finders.

These pages are an absolute treasure, and are, amazingly, all available as free PDF downloads on The Warbler Guide website, though I personally wish the publishers would also sell eastern and western versions as laminated, folded guides. These visual finders show all the species together so you can make a quick guess before thumbing through the species pages. One shows all the warbler faces in profile, another the whole body in profile, a third the side profile from a 45-degree angle, when we see more of the underside and less of the upper body, and a fourth from directly beneath. They repeat the full body profile views with another 2-page spread limited to eastern species in spring, another for them in fall, and have a single 2-page quick finder for western species. Finally, they use Catherine Hamilton’s drawings to compare close-up views of the under-tails of every eastern and every western species.

Of course, the meat of the book is in the 354-pages of species accounts. These include a wide array of photos of each bird with comparison photos of similar-appearing species, listing all the bird’s features and highlighting with a check the features that in and of themselves are diagnostic. For example, if all you can see on a warbler hidden by foliage is a bit of its undertail, but notice black “arrowhead” markings on a white background, you for certain are looking at a Black-and-white. Some straightforward warblers, such as the Black-and-white, are covered in 6-pages, while those with more plumages or which can be easily confused with others, such as the Blackpoll, can have as many as 10, and the Yellow-rumped, which has different plumages for eastern and western forms, is covered in 12 pages.

The Warbler Guide is the perfect book for learning warbler plumages—stunningly beautiful, and fun as well as instructive. And it goes above and beyond that, with the most comprehensive coverage of warbler sounds I’ve ever seen. 


I absolutely love The Warbler Guide's thorough coverage of visual identification. But the book is a game changer in another way, too, providing the best tutorial in learning bird songs and calls I’ve ever seen, with liberal use of spectrographs of sounds, called sonagrams, throughout.

Many people find these graphs of sound scary and confusing. My trusty Golden Guide, the field guide I used in the 1970s when I started birding, is the only field guide I’ve ever seen that uses sonagrams.


I suspect that the reluctance of people to figure them out kept other field guide authors from using them. I intuitively grasped many of the concepts of sonagrams from the start, because I can read music, but it would have been enormously helpful for me when I was starting out to have read The Warbler Guide’s 38-page tutorial, and also to have been able to see a lot of sonagrams for each species, to better grasp the many different songs a single species can produce. This tutorial explains how to go about learning warbler songs, interpreting the sonagrams while listening to the exact corresponding sound via “The Warbler Guide Song and Call Companion,” available as a download for $5.99 via

I downloaded the Companion, which has over 1,000 short sound files, and set it up in iTunes to play each sound on repeat until I advanced it manually to the next sound. Then I read the introductory section about learning warbler sounds while sitting at my computer with iTunes open. This was the perfect way to get a visceral appreciation of how to interpret the spectrographs of bird sounds, and to get a far clearer, more objective understanding of what to listen for while identifying bird sounds than what field guides traditionally show. Even if you can’t afford the $30 Warbler Guide, I strongly recommend checking it out of a library, paying the $6 to download the songs, and doing that tutorial. Learning what to listen for on warbler songs will make distinguishing the songs of other families much easier, too.

After the basic tutorial on how to listen to warblers comes what the authors call their “Song Finder,” in which they group the sonagrams of similar sounds together, so you can see the spectrographs and read their clear explanations of the differences while you listen to the sounds.

After you’ve gone through that amazingly in-depth but enjoyable tutorial, you can head straight to the individual species accounts. Just as The Warbler Guide provides visual comparisons for each bird, it provides sounds, too. The song treatment is extraordinary, covering the different types of songs, call notes, and nocturnal flight sounds for that species along with similar-sounding vocalizations from other species—again, downloading that sound download provides extraordinary in-depth coverage for each species. I would not recommend trying to read and listen to the entire Warbler Guide: after the initial tutorial, I’d prioritize the species by which you want to learn first.

I got a free review copy last year, but love the book so much that I paid for a second copy when the authors were at the popular Ohio birding festival, The Biggest Week in American Birding, this year, so I could get it autographed.

Most of the early fall warblers have passed through the north woods now, though as of September 15, there is still a good variety out there. This would be an excellent time to start reading The Warbler Guide and listening to the companion guide while you get more comfortable identifying Palms, Yellow-rumped, and whatever others are still hanging out. And spend a rainy afternoon or evening on that tutorial at the beginning. Then keep thumbing through those species accounts now and then throughout the winter, and by next spring, you’ll be identifying warblers like a pro. You’ll be so glad you did!

Tom Stephenson & Scott Whittle
Drawings by Catherine Hamilton
Paper Flexibound | $29.95 / £19.95 | ISBN: 9780691154824
560 pp. | 6 x 8 1/2 | 1,000+ color illus. 50 maps.
eBook | ISBN: 9781400846863 (Available July 7, 2013)
Pub date: July 24, 2013

Also, what sounds like a great app for The Warbler Guide will be coming out in time for Christmas. I can’t wait to see it!

Picky Picky Picky

Most of the warbler photos in The Warbler Guide were shot with flash. Based on my observations of my education owl Archimedes when people take his picture in various lighting situations, and on my observations of songbirds at various birding destinations when photographers use flash, I don’t think flash bothers birds much, or even at all, in daylight. But the bright dot or weird reflections in the birds’ pupils on some of the photos did bother my aesthetic sensibilities. The most egregious case was their photo used to illustrate a Canada Warbler’s eye ring. The weird and large white reflection in the pupil could confuse beginners about what and where the eye ring is—I wish they’d photoshopped that out. The Canada Warbler photo they use to illustrate its bill size and shape would have been a better choice for showing the eye ring. The fact that this is the only thing about this entire wonderful guide that I take issue with is pretty darned impressive.

Sunday, September 14, 2014

Harris's Sparrow

(Transcript of a For the Birds program that originally aired on September 28, 2010)

Harris's Sparrow
Harris's Sparrow

Most of my favorite sparrows belong to the genus Zonotrichia. This genus has five species, all fairly large birds with conspicuous markings. The Rufous-collared Sparrow is tropical. 

Rufous-collared Sparrow
Rufous-collared Sparrow

The Golden-crowned Sparrow breeds in the Northwest and winters along the Pacific slope from Canada to Baja California. 

Golden-crowned Sparrow
Golden-crowned Sparrow

Eastern forms of the White-crowned Sparrow breed in northern Canada, and western forms from Alaska down through the mountains—they migrate through in the north woods, and once in a while an individual spends the winter at a feeding station. 

White-crowned Sparrow
White-crowned Sparrow

The White-throated Sparrow breeds in the north woods, is an abundant migrant visiting our feeders in huge numbers in spring and fall, and some winter here. 

White-throated Sparrow
White-throated Sparrow

Harris’s Sparrow breeds in the transition zone between the subarctic boreal forest and the Low Arctic tundra of northern Canada. Some individuals stray into northeastern Minnesota and northwestern Wisconsin every migration, en route to their wintering grounds in the central states from South Dakota down through Texas and northeastern-most Mexico. This is the only species considered endemic to Canada, because it breeds nowhere else on the planet.

Harris's Sparrow
Harris's Sparrow

We in the upper Midwest get to see only a handful of Harris’s Sparrows each year, and then only if we’re lucky. One or two turn up in my mother-in-law’s feeding station in Port Wing, Wisconsin, every May and September, and they usually turn up in my yard at the same time. They’re easy to pick out among the many White-throated Sparrows, but finding them requires that you actually look at each of those sparrows. I hear their song rarely in spring, and I’ve never heard them sing in fall. Like the White-throated Sparrow’s song, Harris’s Sparrow whistles and is easy to imitate. The notes are in a minor key, giving the song a mournful quality. Its call note is pretty similar to the White-throated Sparrow’s, but the quality is different enough that I learned to distinguish them without any trouble, but I did pay attention to both species to notice the quality differences. You can hear their songs, and the songs of just about every North American bird, at Cornell’s wonderful

Harris's Sparrow
Harris's Sparrow

George Miksch Sutton was the first white person to discover a nest of Harris’s Sparrow, near Hudson Bay, in 1932. He wrote:
As I knelt to examine the nest a thrill the like of which I had never felt before passed through me. And I talked aloud! "Here!" I said. "Here in this beautiful place!" At my fingertips lay treasures that were beyond price. Mine was Man's first glimpse of the eggs of the Harris's Sparrow, in the lovely bird's wilderness home. 
Sutton may have had the heart of a poet, but he had the instincts of a 19th Century ornithologist, so he immediately shot the mother and collected the nest and eggs. The bird itself had been “discovered” for science in 1834, when Thomas Nuttall found one in Jackson County, Missouri. Nuttall was a botanist who reportedly never carried a gun, but someone in his party did, and so Nuttall’s bird lies in a drawer in the Academy of Natural Sciences in Philadelphia, serving as the type specimen for the species. I wish they’d kept Nuttall’s name for the bird—he called it the Mourning Finch—but he also gave it the scientific name Zonotrichia querula, which is still its name. Querula is obviously related to “querulous,” which means argumentative, but at that time it also meant whining, fretful, or lamenting, Nuttall’s interpretation of the song. I know I’d be whining and fretful and lamenting if I were a bird in a world where the most powerful species held my life in so little regard. No wonder chickadees bite bird banders so viciously.

Taking revenge
Annoyed Black-capped Chickadee

Friday, September 12, 2014

Struggling with Warblers?

Black-and-white Warbler

When I was a college elementary education major, one of the most valuable things I learned was to never tell kids how easy learning something would be, even if it was something extremely easy for me. When teachers set up an expectation that a new skill or subject is simple, kids who have trouble with it will feel stupid, and kids who do master it won’t feel like they’ve accomplished anything special. I learned that self-esteem comes not from getting pats on the back but from worthwhile accomplishments and mastery of worthwhile subjects. As a teacher, that was the one simple rule I tried never to forget.

Roger Tory Peterson must have been thinking along those lines when he coined the term “confusing fall warblers.” Most of the warblers we see in spring are adult males, who catch our attention with their colors and songs. In fall, warblers don’t sing, and young of the year and adult females together vastly outnumber adult males. And adult males of some species have molted into duller feathers for winter. Knowing that identifying warblers in fall was not as straightforward as in spring made it feel like a fun challenge. Unfortunately, some people think identifying warblers in any season is a scary ordeal.

Nashville Warbler

I started birding in the spring of 1975, and after being out virtually every day, ended the season with 5 warblers on my lifelist—Black-and-white, Nashville, Magnolia, Black-throated Green, and Blackburnian. It was tricky amassing even this little list—I’d see a warbler in a tree, try to notice the basic color pattern and whether it had an eye line, eye ring, wing bars, and other distinctive marks, and then search through the warbler pages hoping to find one with those characteristics. Most of the time when I found a bird in the book that might have been it, I’d look up and the bird would be gone. One time I saw a warbler with bright yellow beneath and black streaks down the breast forming what looked like a necklace. I was sure it didn’t have wing bars and so according to my field guide it had to be a Canada Warbler, but when I looked up in the same branch to confirm my ID, I saw that it had huge wing bars forming a white patch. I searched my book again, and now it was a Magnolia Warbler. This time I managed to go back and forth between the bird and field guide several times to confirm. In retrospect, I’m sure the bird I originally saw really was a Canada, but with my limited experience, I wasn’t quick enough to take everything in, and didn’t know enough about how migrating warblers associate in mixed flocks to even imagine I’d actually seen two different species.

Magnoila Warbler

I spent every free minute that summer birding, and by the end of July had added another four warblers: the Ovenbird, Common Yellowthroat, Yellow Warbler, and American Redstart. Now I was excited about the challenges of those “confusing fall warblers.” I managed to tease out the identities of another four species that fall: Yellow-rumped, Tennessee, Palm, and Wilson’s, ending my first year with 13 warbler species. The following spring I was quicker and more skilled at teasing out identifications, and more than doubled my warbler list to 29 species.

Black-throated Green Warbler

When I wasn’t out birding, I was inside poring over the pages of my field guides, over and over. I mastered warblers a little quicker than many beginners not because I had better eyes or the best books, but because I spent so many hours at it. In his book, Outliers, Malcolm Gladwell says to truly succeed in any endeavor, one must spend 10,000 hours on it. I put in at least 40 or 50 hours a week birding or studying my field guides that first spring, and by the time we were living in Madison, Wisconsin, I was putting in even more time, year-round.

Some people who are smarter or more visually or aurally adept than I have probably mastered birds more quickly, but when it comes right down to it, the way you truly learn birds so identifying them becomes second nature is by putting in the time and work. The delightful thing about birding is that the work involved is so very pleasurable. I may have only identified five species of warblers my first spring, but every one of them made me happy, and the flood of warblers that got away before I could figure them out didn’t frustrate me—they filled me with anticipation of a lovely time in the future when I would recognize them all. This is the 40th year I’ve spent watching warblers, and every moment spent looking at them has been a joy.

Blackburnian Warbler

Thursday, September 11, 2014

Early Cold Front vs. Hummingbirds

Ruby-throated Hummingbird
This hummingbird is taking a rest after filling up at my feeder. S/he is all fluffed up,
so appears very fat. "Lofting" the feathers like this thickens the insulation, keeping the
little bird warmer. The temperature was 46 degrees F. when I took the photo on Sept. 10.

A cold weather system, with gale-force winds, this season’s first frost warnings, and temperature highs in the 40s, was predicted to blow into Duluth in the evening on September 9. I’d had several hummingbirds using and fighting over my feeders for the previous week, and they seemed especially voracious on the 9th, perhaps noticing the dropping barometric pressure. An ant had somehow worked its way into my office window feeder and drowned on the 8th, and when I noticed it in the feeder at midmorning on the 9th, I opened the window and brought the feeder in to change the water. When I came back, one hummer was hovering in the open window. It didn’t fly away as I walked directly toward it and lifted the feeder—once I got the feeder within three or four inches of it, it simply maintained that distance, hovering backwards and sideways as I hung the feeder back up. The little guy was already drinking before I even let go of the feeder, much less closed the window.

I thought most of my hummers would leave on the 9th, but at 6:30 am on the 10th, while it was still quite dark, a hummingbird started feeding at one of my feeders. In order to have found it in the dark, I’m assuming this one spent the night in my yard. All day I had hummingbirds—often two or three at the same time, sometimes engaging in brief chases.

People used to ask me all the time about a “rule” they’d learned, and heard repeated on old TV nature programs, that we should bring in our hummingbird feeders by Labor Day or hummingbirds would linger too late into the fall and end up dying. This year, Labor Day happened to fall on September 1—the earliest date it can fall on. And this year, spring was considerably later than normal, delaying the breeding season for many birds, so if hummingbirds really did schedule their lives around federal holidays, they’d have had an exceptionally short window of time in which to complete all the essential tasks of raising young. Even with the brief breeding season, virtually all adult males and even most adult females had hightailed it out of here by the end of August, including both the adults passing through from further north and those that bred here. But on Labor day this year, at least a few breeding females were almost certainly still recovering from the grueling responsibilities of raising young, and a great many of the young that hatched out this year were still putting on weight and perfecting the life skills they needed before lighting out for the territory.

With so many hummingbirds about and such cold weather headed our way, a lot of people are asking me about whether they should bring in their hummingbird feeders now. But the answer is a simple and emphatic NO. Ruby-throated Hummingbirds have a powerful migratory instinct. They leave, one by one, as soon as their bodies are in migratory readiness.

Keep your feeders clean and the sugar water fresh. During cold, wet conditions, make the mixture a little stronger—about a third of a cup of sugar per cup of water. That may help any birds that had bad luck during the breeding season make it through these early cold spells. When temperatures rise again, at least some insects will become active again, and unless there’s a killing frost, flowers will still have some nectar. One by one, as soon as the birds have enough body fat, they’ll leave. Except for outliers that look completely different from others, it’s impossible to know which of our birds are sticking around for a few days to gain weight and which are grabbing a quick meal as they pass through, but hummingbird scientists and my own experience guarantee that the birds capable of migration will, indeed, head out as soon as their fat reserves allow. The trick will be to get enough food to build up those reserves. In a cold autumn, our feeders can make the difference between life and death for some of these irreplaceable birds.

Wednesday, September 10, 2014

Audubon's Climate Change Report

Common Loon

I’ve been looking forward to September 9 for months—it was the day the 2014 State of the Birds report was due to come out. This is the fifth edition of this annual report, put together by a large group of non-profits, such as the Cornell Lab of Ornithology, the American Bird Conservancy, Audubon, and Ducks Unlimited, working with government agencies such as the U.S. Fish and Wildlife Service, the U.S. Forest Service, the National Park Service, and  Environment Canada. I got to help with the first issue, released in 2009 when I was serving as the science editor at the Cornell Lab of Ornithology, and know how careful the group is at reaching its conclusions. 

The report this time has some disturbing findings. Their “Watch List” of vulnerable species in the United States and Canada, each meeting their criteria of a combination of high rate of population decline, small population size, small geographic range, and significant future threats to sustainable populations, includes 230 species.

Baltimore Oriole

First thing in the morning on September 9, my email box became inundated with questions from people about the predicted loss, by the end of this century, of nesting loons in Minnesota and Baltimore Orioles in Maryland, and naturally I assumed they were referring to the State of the Birds report. But it turns out Audubon chose the same day to release a completely separate Climate Report

Audubon put together a comprehensive study, using current models of how the changing climate is and will continue to change habitat, to see how climate change could affect the ranges of 588 North American bird species. Their models indicate that 314 species will lose more than 50 percent of their current range by 2080. Of them, 126 species are projected to lose more than 50 percent of their current range by 2050 if the changes due to global warming continue at their current pace.

Common Loon

To get the attention of the media, Audubon used two extremely popular state birds—the Baltimore Oriole and the loon—as their poster children for the report. And almost all the people writing me were asking about our beloved loon. Current projections by Audubon for the Common Loon indicate that by 2080, the breeding range will retract as water temperatures rise. Loons require extremely clear water for catching fish, and the algae growth associated with warmer temperatures will little by little force breeding loons out of Minnesota and Wisconsin. Unfortunately, loons already breed at the farthest northern reaches of the continent, so as they lose ground in the southern part of their range, they can’t expand to the north. By 2080, they’re expected to have only 44 percent of their breeding range remaining.

Audubon used Christmas Bird Count data to indicate winter ranges of birds, making the situation for loons sound even direr, because Audubon predictions indicate that loons will lose 80 percent of their winter range. But really, loons are often still migrating during much of the Christmas Bird Count period—the vast majority of our loons winter on salt water in the Atlantic or the Gulf of Mexico. Of course, that situation is also worrisome, because of major changes in fish populations as ocean water temperatures rise.

The Audubon projections for Baltimore Orioles do, indeed, show the breeding range moving north and out of Maryland, but nevertheless, Baltimore Orioles are projected to enjoy an overall range increase, as cottonwoods retract from a small area but expand into what is now boreal forest. Through 2080, Audubon projects that Baltimore Orioles will enjoy a 76 percent increase in suitable breeding range.

That increase will come at the expense of birds depending on what is now boreal forest. Our beloved Northern Hawk Owl—a wonderfully confiding and charismatic visitor in winter and occasional breeder in the bog country just north of Duluth—is among the 30 species threatened with the loss of more than 90 percent of their current range by 2050.

What can we do to help? Conserving energy will not only reduce the carbon gases we send into the atmosphere but reduce a whole suite of other dangers to birds caused by extracting, transporting, and burning fossil fuels. It’s simply the right thing to do.

Northern Hawk Owl

Tuesday, September 9, 2014

Predation and Hummingbirds

Resting Ruby-throated Hummingbird
All the photos shown in this blog entry were taken within 4 seconds when the bird was "resting" but
looking every which way

I’ve been a member of several professional ornithological societies since the 1970s, and love reading the scientific papers in their journals. Of course, some studies are stronger than others. When my children were babies, I often read journal articles aloud to them while I was nursing them or rocking them to sleep, and remember chuckling about the conclusions of one particular paper from 1985 claiming that hummingbirds do not have natural predators. The paper summarized the authors’ literature search in which they could find only 13 documented cases ever of hummingbird adults being taken by predators, and concluded that “hummingbirds in North America do not have ‘natural predators’ in the usual sense.”

Most of the studies I read in journals correspond to and provide insights into my own observations, but not this one! I could see hummers right outside my own window taking breaks after a stomach-filling drink. They never tucked in their head and just snoozed, but were ever vigilant, looking every which way every moment. In some extreme temperature situations, hummingbirds do go into a deep sleep called "torpor," but that's only when the physiological costs of maintaining their body temperature are too high under the current weather conditions, and presumably they find as safe a place as possible to retreat to for those times when they can't be watching for danger. 

Now that I take photos, I often set my focus on a sitting hummer and click away as fast as my camera’s burst function allows. Whether a hummer is resting or preening, in any single burst of pictures I’ll get images of it looking every which way. Of course, just like chickadees, warblers, and other sensible birds, hummingbirds have to get used to me at the window before they will allow me to photograph them. They fly off at any unexpected sound or movement from any direction. Hummingbirds are extraordinarily pugnacious, and chase off competitors, so some of this vigilance is almost certainly to help them discover rivals for their food resources, but their flying off at any unexpected sound or movement is indicative of wariness, too. And like my backyard chickadees, they have the intelligence to figure out through experience and observation which sights and sounds indicate a competitor, which might pose a danger, and which animals and people are probably innocuous. Even though some individual hummingbirds come to ignore my presence, just like my chickadees, these ostensibly less-wary hummingbirds fly off the instant I do anything unexpected.

Resting Ruby-throated Hummingbird

I don't normally take issue with scientific papers, especially those written almost three decades ago. But this particular paper, written by Miller and Gass (of Yale and the University of British Columbia), and titled “Survivorship in Hummingbirds: Is Predation Important?” has been quoted extensively in the literature since its 1985 publication in The Auk, despite some papers since then taking issue with the conclusions. Even the Ruby-throated Hummingbird entry in The Birds of North America Online (BNA), published and kept up to date by the American Ornithologists’ Union and the Cornell Lab of Ornithology, refers to it even as it cites several cases of predation not mentioned in it. 

I started looking specifically at this paper after reading a chapter about hummingbirds in a best-selling book published just this year, The Thing with Feathers: The Surprising Lives of Birds and What They Reveal about Being Human. Noah Strycker, the author, quotes extensively and unquestioningly from the original paper, so I tracked it down to see whether I was misremembering, and maybe it was better than my vague lingering impression. But no, in fact it was even worse.

The authors really did claim to have done a thorough search of the literature and really did claim to have been able to find only 13 cases ever of predators attacking hummingbirds in North America as of 1985. But just using my home references and a quick search of the Internet, I found several reports of predation on hummingbirds published before 1985 that they didn’t include. And even worse, in the case of at least one paper, they seem to have read no further than the title.

Resting Ruby-throated Hummingbird

Miller and Gass cite a 1976 paper in The Condor by Sally Spofford titled “Roadrunner Catches Hummingbird in Flight,” in which she discusses a case she witnessed of a Greater Roadrunner grabbing a Black-chinned Hummingbird in mid-air at her Arizona feeder. That accounts for the single case of roadrunner predation cited in Miller and Gass, but Spofford also wrote, in the same brief paper, that on another occasion, she had seen a roadrunner pounding a black-chinned hummer to death on the ground, though she didn’t know whether that one had captured it in mid-air or not, and wrote that she’d found the tail feathers of a Blue-throated Hummingbird female that had been ripped out by a roadrunner—in that case, the little bird got away and she had seen it without its tail feathers afterwards. Of their 13 cases of predation, Miller and Gass cite only one case ever of roadrunner predation on hummers. Their omission of two cases in the very paper they cite makes their total off by 15 percent—a serious error that should have been picked up in the peer review process and corrected before publication.

But it also begs the question why the authors believed that a literature search could possibly include every case of predation on hummingbirds in the first place. Back in 1982 when Russ and I birded in Arizona, I remember people saying that roadrunners were known to snap up hummingbirds, and every account I’ve ever read about roadrunners, including those published before 1985, mentioned that they feed on small birds. It was common knowledge. Sally Spofford’s paper made it into a major journal simply because she had observed a roadrunner flying off her roof to take a hummingbird while both birds were in flight, rather than snapping at it while the roadrunner was perched or on the ground. That technique of roadrunner predation hadn’t been known before. Now, of course, thanks to email and the Internet, along with citizen science projects, we’ve got a lot more easy access to sightings of predation, at least for backyard birds, than was possible for Miller and Gass. The Birds of North America Online's entry for the Greater Roadrunner states “Frequently ambush hummingbirds at feeders.” I’ve read accounts from many people in the Southwest who’ve had to take in their hummingbird feeders because roadrunners were snapping up their hummers.

Resting Ruby-throated Hummingbird

Cases of predation on hummingbirds by insects and frogs were completely dismissed by Miller and Gass as “unusual or even bizarre,” although of the 13 cases they cite in their own paper, 6—almost half—are by insects and frogs. Ruby-throated Hummingbirds often feed on jewelweed at the edge of ponds and streams, so it isn’t surprising that sometimes a frog grabs one. In one of his Hilton Pond reports from 2007, Bill Hilton, Jr., wrote about watching a frog leap at but miss a hummingbird.

With regard to insects, again, it was easy for me to find cases in the literature from well before 1985. In his Audubon Society Encyclopedia of the Birds of North America, published 5 years before the paper, John K. Terres found three cases in the literature of Ruby-throated Hummingbirds being taken by praying mantises—one more than Miller and Gass found. Nowadays cases of praying mantises killing hummingbirds are well known. My quick google search of “praying mantis and hummingbird” found gruesome photos of at least 10 different cases of these predatory insects feeding on hummingbirds on just the first screen of results! That information was obviously not available to Miller and Gass, but should be known by anyone writing about hummingbird predation in 2014. 

Miller and Gass didn't mention a 1934 case cited in Bent’s Life Histories of a Ruby-throated Hummingbird on the ground in the clutches of a large dragonfly. Duluth’s own Pershing Hofslund had a paper published in The Loon in 1977 titled “Dragonfly attacks and kills a Ruby-throated Hummingbird,” about another incident of that. Those cases should have been mentioned in the 1985 paper—again, I'm surprised that this wasn't picked up in peer review. And again, nowadays it’s easy to find more cases. Bill Hilton, Jr., shows photos of one couple that came upon a hummer pinned down by a robber fly, already missing a round patch of feathers on its skull by the time they rescued it. (Robber flies often eat just the head contents of large prey.)

Miller and Gass don’t mention predation by fish—something I once witnessed personally, and something cited in Bent’s Life Histories from a 1922 report by Lockwood. They also don’t mention what The Birds of North America Online emphasizes as the most common predator of hummingbirds near human activity, the domestic cat.
Resting Ruby-throated Hummingbird

The Thing with Feathers emphasizes that hummingbirds are immune from even bird-hunting raptors, too. “Because bite-sized hummers are so quick and light, they don’t have to worry much about hawks and other attackers.” It is indeed hard for hawks to grab a hummingbird, and the payoff is indeed less than grabbing, say, a chickadee or warbler, but then again, the payoff for catching those little songbirds is less than grabbing a Blue Jay. That hardly means a Merlin or American Kestrel will pass up a chance to snatch one of those little birds—raptors grab for anything they can. Dragonflies are just about as quick and even lighter than hummingbirds, yet are a major food source for kestrels migrating through Duluth. Frank Nicoletti published a paper in 1996 in The Loon showing how the migration of both American Kestrels and even the bigger, tougher Merlins correlates with green darner dragonfly movements at Hawk Ridge. So imagining that either species would pass on a “bite-sized hummer” is ridiculous. Miller and Gass do cite one known case of a Ruby-throated Hummingbird in the stomach contents of a Merlin—a case also reported in Arthur Cleveland Bent’s Life Histories of North American Birds. But Bent also reports a Rufous Hummingbird taken by a Merlin—yet another published incident not mentioned in Miller and Gass's paper. The Birds of North America Online cited known predation on Ruby-throated Hummingbirds by Mississippi Kite, Sharp-shinned Hawk, American Kestrel, Merlin, and Loggerhead Shrike. Bill Hilton, Jr., a hummingbird bander and recognized authority on them, also lists herons, egrets, gulls, large flycatchers, jays, tanagers, grackles, and orioles to the list of known avian predators on hummingbirds in one of his Hilton Pond reports from 2007. 

Living under Hawk Ridge as I do, and having counted raptors at the Ridge and from the Lakewood Pumping Station, I’ve personally witnessed Sharp-shinned Hawks, Merlins, and American Kestrels chasing hummers several times over the years, though they zipped behind vegetation before I could see how any of the chases ended. I’ve also never seen how a chase ended when a sharpie or Merlin was chasing a warbler. I’ve occasionally seen these raptors feeding on birds, but unless I’m very close or their meal is something big like a robin or jay, it’s usually hard to identify the tiny morsels. I suspect any self-respecting Merlin could rip apart and swallow a hummingbird as they do dragonflies, on the wing. People counting migrating birds seldom have the leisure to track birds for any length of time, and it's rare to see any predation events at any time, so my never having seen dead hummers in the talons of raptors hardly indicates that it never happens.

Some researchers have accepted Miller and Gass even while noting that hummingbirds show a lot of predator avoidance behaviors. Steven L. Lima wrote in his paper, "Energy, predators and the behavior of feeding hummingbirds" published in July 1991 in Evolutionary Ecology:
When Anna's hummingbirds (Calypte anna) are faced with an obstructed view of their surroundings, they engage in behaviour suggestive of anti-predatory vigilance. In doing so, they voluntarily reduce their rate of energy intake. These birds also forgo better feeding opportunities that occur close to the ground, where observations suggest they are wary of opportunistic predators such as roadrunners (Geococcys californianus). While energy-based concepts will remain useful in the study of hummingbird feeding behaviour, the lack of predation on these birds should not be equated with an insensitivity to the risk of predation.
The conclusions of Miller and Gass's paper were also specifically addressed in a paper by Zenzal and others published in 2013 in the Southeastern Naturalist, “Observations of Predation and Anti-predator Behavior of Ruby-throated Hummingbirds during Migratory Stopover.” The new paper pretty much concludes exactly what I do regarding predation during migration—that it is, indeed, one of the hazards facing migratory hummingbirds when passing over or spending time in migratory stopovers. These authors cite both cases of known predation and observations of the wariness of hummingbirds in their study areas.

As far as I can tell from observations at home, predation is also a factor for nesting hummingbirds. Merlins nest in my neighborhood, and the summering adult hummingbirds I’ve observed in my yard are just as vigilant as those passing through during migration. Merlins are exceptionally vocal, and anytime I’ve ever heard one call, any hummers at my feeder have instantly zipped away.

Resting Ruby-throated Hummingbird

Miller and Gass write that “the exponential increase in field research on hummingbirds in the last decade and the lack of a corresponding increase in reports of predation” supports their case that predation on hummers is exceptionally rare. But scientists should realize that for a paper to be published in a journal, it must show something new, as Spofford's observation of the roadrunner grabbing a hummingbird on the wing did. Also, although studies of hummingbirds have, indeed, increased, studies involving killing raptors to examine their stomach contents have not only decreased—they've virtually ended. Miller and Gass's argument reminds me of the patently ridiculous argument I had to deal with back in the 1980s when an ornithologist claimed birds were no longer being killed at communications towers, because he’d done an exhaustive search of The Auk, and no papers had been published about it in a couple of decades. He was clearly looking only at the titles of papers. It became well established by the 1960s that migrating birds were being killed at towers in large numbers at night, especially in foggy conditions, so by the 80s, that was not a publishable new finding. Yet even in the 80s, The Auk was publishing papers in which dead birds picked up under communications towers constituted a significant portion of data sets used to assess the timing of migration, how much body fat migrants carry, and other issues only tangentially related to tower kills. 

It would be prohibitively difficult with the technology from 1985, or even today, to do a systematic study of predation on hummingbirds, just like it would be prohibitively difficult to do a systematic study of predation on, say, Bay-breasted Warblers or Golden-crowned Kinglets, but that hardly means it makes sense to assume that predation on those species could possibly be negligible. Like loons and a few other relatively long-lived species, hummingbirds produce only 2 eggs per clutch. And like other species with low reproduction rates, they have developed strategies for minimizing losses to predation. A hummingbird’s size and speed do, indeed, help it avoid being taken by predators, but its intelligence and wariness are even more critical. A single error at a flower near where a frog is sunning, flying a bit too close to the water where a large-mouth bass happens to be near the surface, staying at a feeder a second too long as a Merlin wings by, not noticing a roadrunner lurking in a flower bed—any momentary error can be the last for any bird, including hummingbirds.

I love seeing writers referring to the scientific literature in books and magazine articles for general readers, and know that any conclusions I make from my own personal experiences can be colored by my expectations, so I try to be careful and fair when discounting any study. But really, it doesn’t make sense to base a whole chapter of a major book on a study from almost 30 years ago that has since been refuted in the literature—especially regarding birds that give us so many opportunities for personal observation and about which so much information is easily available on the Internet. There are many interesting things in the book The Thing with Feathers, but the chapter on hummingbirds is making me read the rest of it with a very large grain of salt.

Resting Ruby-throated Hummingbird

Friday, September 5, 2014

Mark Twain's Autobiography: Hunting Pigeons and Turkeys

I’ve been reading Mark Twain’s autobiography—I got the hardbound book a few years ago, and have now been listening to it as a “books on tape.” Frustratingly, whoever put together the index was not anticipating that ornithologists would be interested in reading Twain’s observations of birds. When I hear on the CDs something about a bird, I can’t find the entry in the book, but fortunately, thanks to the Mark Twain Project, I can easily track it down on line. 

With the recent 100th anniversary of the extinction of the Passenger Pigeon, I found Twain’s childhood memories of them fascinating. He wrote, 

I remember the pigeon seasons, when the birds would come in millions, and cover the trees, and by their weight break down the branches. They were clubbed to death with sticks; guns were not necessary, and were not used.
Passenger Pigeon
Passenger Pigeon

Twain also wrote a hilarious account of hunting for turkeys. I’ve had to abridge it for the radio, but here's the entire story. I’ve only edited out parentheses and page numbers from the Mark Twain Project pages.

In the first faint gray of the dawn the stately wild turkeys would be stalking around in great flocks, and ready to be sociable and answer invitations to come and converse with other excursionists of their kind. The hunter concealed himself and imitated the turkey-call by sucking the air through the leg-bone of a turkey which had previously answered a call like that and lived only just long enough to regret it. There is nothing that furnishes a perfect turkey-call except that bone. Another of Nature’s treacheries, you see; she is full of them; half the time she doesn’t know which she likes best—to betray her child or protect it. In the case of the turkey she is badly mixed: she gives it a bone to be used in getting it into trouble, and she also furnishes it with a trick for getting itself out of the trouble again. When a mamma-turkey answers an invitation and finds she has made a mistake in accepting it, she does as the mamma-partridge does—remembers a previous engagement and goes limping and scrambling away, pretending to be very lame; and at the same time she is saying to her not-visible children, “Lie low, keep still, don’t expose yourselves; I shall be back as soon as I have beguiled this shabby swindler out of the county.” 
When a person is ignorant and confiding, this immoral device can have tiresome results. I followed an ostensibly lame turkey over a considerable part of the United States one morning, because I believed in her and could not think she would deceive a mere boy, and one who was trusting her and considering her honest. I had the single-barrelled shot-gun, but my idea was to catch her alive. I often got within rushing distance of her, and then made my rush; but always, just as I made my final plunge and put my hand down where her back had been, it wasn’t there; it was only two or three inches from there and I brushed the tail feathers as I landed on my stomach—a very close call, but still not quite close enough; that is, not close enough for success, but just close enough to convince me that I could do it next time. She always waited for me, a little piece away, and let on to be resting and greatly fatigued; which was a lie, but I believed it, for I still thought her honest long after I ought to have begun to doubt her, long after I ought to have been suspecting that this was no way for a high-minded bird to be acting. I followed, and followed and followed, making my periodical rushes, and getting up and brushing the dust off, and resuming the voyage with patient confidence; indeed with a confidence which grew, for I could see by the change of climate and vegetation that we were getting up into the high latitudes, and as she always looked a little tireder and a little more discouraged after each rush, I judged that I was safe to win, in the end, the competition being purely a matter of staying power and the advantage lying with me from the start because she was lame. 
Along in the afternoon I began to feel fatigued myself. Neither of us had had any rest since we first started on the excursion, which was upwards of ten hours before, though latterly we had paused a while after rushes, I letting on to be thinking about something, and she letting on to be thinking about something else; but neither of us sincere, and both of us waiting for the other to call game but in no real hurry about it, for indeed those little evanescent snatches of rest were very grateful to the feelings of us both, it would naturally be so, skirmishing along like that ever since dawn and not a bite in the meantime; at least for me, though sometimes as she lay on her side fanning herself with a wing and praying for strength to get out of this difficulty a grasshopper happened along whose time had come, and that was well for her, and fortunate, but I had nothing—nothing the whole day. 
More than once, after I was very tired, I gave up taking her alive, and was going to shoot her, but I never did it, although it was my right, for I did not believe I could hit her; and besides, she always stopped and posed, when I raised the gun, and this made me suspicious that she knew about me and my marksmanship, and so I did not care to expose myself to remarks. 
I did not get her, at all. When she got tired of the game at last, she rose from almost under my hand and flew aloft with the rush and whir of a shell and lit on the highest limb of a great tree and sat down and crossed her legs and smiled down at me, and seemed gratified to see me so astonished. 
I was ashamed, and also lost; and it was while wandering the woods hunting for myself that I found a deserted log cabin and had one of the best meals there that in my life-days I have eaten. The weed-grown garden was full of ripe tomatoes, and I ate them ravenously though I had never liked them before. Not more than two or three times since have I tasted anything that was so delicious as those tomatoes. I surfeited myself with them, and did not taste another one until I was in middle life. I can eat them now, but I do not like the look of them. I suppose we have all experienced a surfeit at one time or another. Once, in stress of circumstances, I ate part of a barrel of sardines, there being nothing else at hand, but since then I have always been able to get along without sardines.

Wild Turkey
Wild turkey