Category Archives: Bird Behavior

Fewer Hybrid Golden-Wings Thanks to Climate Change

Golden-winged warbler (photo from Wikimedia Commons)

9 January 2023

Golden-winged warblers (Vermivora chrysoptera) and blue-winged warblers (Vermivora cyanoptera) do not look or sound alike but they are well known to hybridize. Because of this ornithologists used to worried that the more numerous blue-winged warbler would force the golden-winged out of existence. Then a 2016 genetic study showed no need to worry — they are very closely related. Now a 2022 study shows that hybridization will become less likely thanks to climate change.

Blue-winged warbler (photo from Wikimedia Commons)

In 2016 we learned that golden-winged and blue-winged warblers are virtually the same bird — 99.97% genetically alike! No wonder they interbreed.

Put another way, the striking visual differences between Golden- and Blue-winged warblers could be considered akin to the differences between humans with and without freckles. Golden-wings and blue-wings have even less genetic differentiation than two subspecies of the Swainson’s Thrush.

All About Birds: Mixed Wing Warblers: Golden-wings and Blue-wings are 99.97 percent alike genetically

Their colors and songs fooled us so we called them hybrids and even named them Brewster’s and Lawrence’s warblers, but the difference is moot to the birds themselves. This illustration embedded from All About Birds, shows their four color phases governed by a dominant/recessive throat-color gene.

If you’re still worried about hybrids, the newest study should put your mind at ease. Entitled “Change in climatically suitable breeding distributions reduces hybridization potential between Vermivora warblers,” it maps the birds’ past and present breeding ranges and models their future under 6 climate scenarios.

Historically (1932-1997) the warblers’ ranges overlapped a lot but by 2012-2021 it was evident they were moving apart. Climate change has moved the golden-wing’s preferred cooler habitat to the north and higher elevations.

The future will move their ranges even more, shown in six scenarios below. The left column shows climate altering emissions peaking in 2040 and then declining. The right column shows emissions continuing to rise through 2100.

Predicted climate suitability for Golden-winged Warblers (yellow) and Blue-winged Warblers (blue) distributions under future climate scenarios (

Unfortunately climate change may force one or both warblers out of existence. Map (d) is the only happy one for both of them but they will disappear as breeding birds in western Pennsylvania.

Don’t worry about golden-winged warbler hybrids. The real problem is climate change.

* Read more about golden-wing and blue-wing relatedness in All About Birds, Living Bird Magazine: Golden-Winged And Blue-Winged Warblers Are 99.97 Percent Alike Genetically.

* See the breeding range study at Wiley Online: Change in climatically suitable breeding distributions reduces hybridization potential between Vermivora warblers.

(photos from Wikimedia Commons, illustration embedded from All About Birds, maps are open access at Wiley Online Library)

White-throated Sparrows Have Four Sexes

White-throated sparrow colors and sexes — green arrows show the only combinations that can mate successfully (photos from Wikimedia Commons)

8 January 2023

White-throated sparrows (Zonotrichia albicollis) come in two color morphs with either white-striped or tan-striped heads. The color tells us nothing about the sex of the bird because both morphs contain males and females. Last week a new article about a 2016 study reiterated the white-throated sparrow’s affinity for mating with the opposite color morph. It’s deeper than just a preference. These birds cannot reproduce with their own color.

Thirty years of research by Elaina Tuttle and Rusty Gonser into the genetics and behavior of white-throated sparrows revealed a mutation in chromosome 2 that makes it impossible for same-color-morph birds to reproduce. The birds seem to know this and only look for mates among birds of the opposite color. Instead of half the population as possible mates, fellow researcher Christopher Balakrishnan points out that “One individual can only mate with one-quarter of the population. This bird acts like it has four sexes.”

  • White-stripe Male
  • Tan-stripe Male
  • White-stripe Female
  • Tan-stripe Female

A system of four sexes is quite rare and there’s a reason. As Balakrishnan says, “it is evolutionarily unstable and one of these alleles will ultimately go extinct.”

White-throated sparrows have declined 69% in the U.S. over the past 50 years and overall (including Canada) by 33%. Are they declining because of habitat loss? window kills? Is their four-sex system also taking a toll? If so they’re probably the only species with that challenge.

Read more in these two articles where I obtained the quotes above: IFLScience: Meet The Sparrow With Four Sexes and NATURE: The sparrow with four sexes.

(four photos above are from Wikimedia Commons at these links: top left, top right, bottom left, bottom right)

Winter Birds at the Beach

Sanderlings in December (photo from Wikimedia Commons)

3 January 2023

When we think of the beach in winter it sounds pretty bleak but not if you’re a birder. Shorebirds, sea ducks, loons and gulls leave the icy north to winter on the Atlantic and Pacific coasts where they hang out on beaches or just offshore, especially near jetties.

If you can’t travel far from Pennsylvania, visit the New Jersey shore to see thousands of wintering birds. GetToKnowNature describes what you’ll see in her video “Welcome to the beach in winter.” Click here or on the screenshot below to see it on Instagram (you don’t need an account to see it) or here for YouTube.

Screenshot from GetToKnowNature winter beach video on Instagram

(photo from Wikimedia Commons, screenshot from GetToKnowNature video on Instagram)

Drunk On Fermented Fruit

Cedar waxwing in Ohio (photo from Wikimedia Commons)

28 December 2022

After five days of extremely cold weather the temperature is rising into the 40s today and will stay above freezing in the week ahead. Hard fruits that were softened by the freeze are now poised to ferment in warmer weather. Soon we may see drunken birds.

Birds leave crabapples and Callery pears on the trees in November because they’re too hard to eat. Freezing breaks down the starches into sugars and when the fruit thaws it is soft and yummy. However yeast gets into the fruit and ferments it. Birds gobble up the soft tasty fruit. If they eat too much they get drunk.

Callery pear fruit, before and after freezing (photos by Kate St. John)

When abundant rowan berries fermented in Gilbert, Minnesota in October 2018, waxwings gorged on them and became quite drunk.

video from Fox 9 Minneapolis-St. Paul on YouTube

This black-billed magpie didn’t care that he was eating fermented apples until he could barely walk. He staggers among the apples and is only slightly more agile by the end of the video.

video from @ViralSnareRightsManagement on YouTube

Pumpkins are a fruit and, yes, they can ferment. When they do, squirrels get drunk.

Discarded pumpkins in Bloomfield, Dec 2020 (photo by Kate St. John)

video from @ShadiPetosky on YouTube

In 2015 a study reported that fermented fruit is becoming more common because of climate change. There’s more news in this vintage article.

(photos by Kate St. John and from Wikimedia Commons, videos embedded from YouTube; click on the captions to see the originals)

Hand Feeding The Birds

Screenshot of female northern cardinal feeding from her hand, Jocelyn Anderson Photography @JocAPhotography

27 December 2022

When Michigan photographer Jocelyn Anderson (@JocAPhotography) takes a walk in the park she brings her camera and a pocketful of shelled peanuts, sunflower seeds and suet nuggets. While balancing her camera she films the birds eating out of her hand in beautiful closeups.

Before last week’s cold snap the birds were very hungry and very active as seen in the screenshot above and her video below. (Videos are in slow motion.)

A male red-bellied woodpecker arrived alone. As he lands you can see the pale red patch on his belly that gives him his name.

Days later it was too cold for bare hands so she offered the food on her mitten.

See more of Jocelyn Anderson’s photos and videos @JocAPhotography on Twitter. Visit her photo website where you can learn “How to Hand Feed Birds.”

(screenshot and videos by Jocelyn Anderson (@JocAPhotography)

Down to the Wire: Where Are The Crows?

Crows at a staging location on their way to the roost, Nov 2016 (photo by Kate St. John)

19 December 2022

Pittsburgh’s Christmas Bird Count is only 12 days away on 31 December 2022 so my search for Pittsburgh’s winter crow roost has taken on some urgency. I need to find their roost and a good vantage point for counting them, all before New Year’s Eve. Please let me know where you see crows overnight or after sunset, especially next week (after Christmas)!

Several of you responded to my 5 December blog, Help Me Find Pittsburgh’s Winter Crows, with these helpful dates and locations.

  • mid-November: On the Cardello Building near the West End Bridge
  • Dec 8 & 9: Flying over Mt. Oliver/Allentown just before dawn
  • Dec 11 and 14: roosting at City View, PPG Paints Arena and Cambria Hotel area
  • Dec 14: Big flocks flying east to west over Kennard Playground as viewed from Elmore St

I’ve checked from City View to the Hill District but haven’t made it to Mt. Oliver/Allentown yet. This map includes your sightings in orange and mine in yellow.

Pittsburgh crow roost map as of 19 Dec 2022 (screenshot Google map plus markup)

If I’ve learned anything it’s that the crows keep moving their roost, sometimes rather far. They’ve already abandoned the PPG Paints Arena area and have nudged their Hill District roost further north. Where will they be 12 days from now?

The other mystery is that I’ve only seen 5,000 of them. Does Pittsburgh have 10,000 to 20,000 crows as we did in years past? Where are the other 5,000 to 15,000?

Please let me know where you see crows overnight or after sunset. I’ll be out of town over Christmas and am going to miss the next crow move (they will change location when it’s only 7 degrees on Fri & Sat nights). Your help is really crucial.

I hope to count 10,000 to 20,000 crows on New Year’s Eve.

(and yes, I need to check Mt. Oliver/Allentown!)

(photo by Kate St. John, annotated map screenshot from Google Maps, click on the caption to see the original)

A Rare Bird at Any Time of Year

Yellow-throated warbler at suet feeder in St. John’s, Newfoundland, 9 Dec 2022 (photo by Felip1 via Flickr Creative Commons license)

16 December 2022

A yellow-throated warbler (Setophaga dominica) would not be rare in Pittsburgh in early May but to see one in Canada in December is amazing.

This bird was photographed in St. John’s, Newfoundland on 9 December by Phillip (Felip1).

It’s not a very sharp picture but enough to identify him: a Yellow-throated warbler. He showed up for some suet early this morning.

I was half-expecting him. He had been visiting a suet feeder a couple of hundred metres away from us a few days ago. And one of the flickers had chopped up lotsa suet for him from the suet holder above. Those flickers are pigs but the other birds appreciate it.

Even though it is mid-December, the weather’s been mild and there are a half-dozen warblers who have apparently decided to try their luck to spend the winter around this town, St. John’s, Newfoundland, when all their relatives decamped a couple of months ago for more southern climes.

Felip1: Late Warbler, 9 December 2022

Pennsylvania is typically the northern limit of the yellow-throated warbler’s range and it’s a short-distance migrant to Florida and the Caribbean. St. John’s, Newfoundland is not even on the map (red arrow points toward it) but Newfoundland is about as far as Florida if you’re migrating from PA in the wrong direction.

Yellow-throated warbler range map from Wikimedia Commons. red arrow points toward St. John’s, Newfoundland which is off the edge of the map

The presence of this bird, one of half a dozen warblers in St. John’s in December, might be an after effect of Hurricane Fiona … and might not.

In any case its splash of yellow is a happy sight on a dreary day.

(photo by Felip1 on Flickr, Creative Commons non-commercial License)

Seeing or Hearing Birds Makes Us Happier

Canada warbler, 2011 (photo by Cris Hamilton)

14 December 2022

Just one week away from the winter solstice birds are not abundant in Pittsburgh and are certainly not singing, but it’s still good for us to seek them out. A new study says that the sight or sound of birds makes us happier.

Published in October in Scientific Reports, the study enlisted 1,200+ participants in the UK, EU and US. Using a phone app called Urban Mind, participants were asked three times a day whether they could see or hear birds plus questions about their mental well-being. The data showed that being near birds improved the mental health of people both with and without depression. The good mood lasts 8 hours.

It certainly works for me. I was recently upset by sad news of a friend and could not stop thinking about it. Hours later, still mourning, I went out for a walk. While my brain was busy with sadness a noisy crow flew over and drew my attention, “Hey!” I stopped to look at the crow and my brain shifted gears. Already I felt happier. Thank you, crows.

American crows (photo from Wikimedia Commons)

Despite gray December days, take the time to get outdoors or watch your bird feeders for a splash of happiness.

Northern cardinal in winter, Jan 2019 (photo by Steve Gosser)

In the meantime get happy with the sound of a northern cardinal in May.

Read more about the study at Being Around Birds Boosts Our Mental Well-Being Even 8 Hours After Hearing Them.

(photos by Cris Hamilton, Wikimedia Commons and Steve Gosser)

Crows Can Think Recursively

American crow (photo from Wikimedia Commons)

6 December 2022

We humans used to think we were very special and very smart because we had language while other species did not. When we learned that other animals had language too our hubris diminished slightly but we still believed in our uniqueness: We were the only species that could think recursively.

In The Recursive Mind (Princeton University Press, 2011) Michael C. Corballis describes “a groundbreaking theory of what makes the human mind unique.”

The Recursive Mind challenges the commonly held notion that language is what makes us uniquely human. In this compelling book, Michael Corballis argues that what distinguishes us in the animal kingdom is our capacity for recursion: the ability to embed our thoughts within other thoughts. “I think, therefore I am,” is an example of recursive thought, because the thinker has inserted himself into his thought. Recursion enables us to conceive of our own minds and the minds of others. It also gives us the power of mental “time travel”—the ability to insert past experiences, or imagined future ones, into present consciousness.

Princeton University Press Book description: The Recursive Mind

Our uniqueness suffered another blow last month when a study published in Science Advances revealed that crows can think recursively, too.

What is recursive thinking and how did crows prove they can do it?

Recursive thinking means “embedding thoughts within other thoughts” like nested Russian dolls.

Nested Russian Matryoshka doll (photo from Wikimedia Commons)

For instance, my sentences are often recursive. If you put parentheses around the complete embedded thoughts they can be thrown away without hurting the sentence. As in: “Our uniqueness suffered another blow last month when a study (published in Science Advances) revealed that crows can think recursively, too.”

To test the birds researchers trained two crows to peck pairs of brackets in a center-embedded recursive sequence. They used differently shaped brackets, some in proper order, some not. Like this:

[ { () } ] or { ( [ ) } ]

The brackets make my head hurt. It’s easier to see in this diagram.

If you put brackets around the starting and ending “thoughts” you’ll see a pattern. The brackets fail in the non-recursive example.

According to Scientific American, after the crows were trained to peck bracket pairs, the researchers tested the birds’ ability to spontaneously generate recursive sequences on a new set of symbols. The birds were successful about 40 percent of the time, on par with 3 to 4 year olds in a 2020 study. The crows were better than monkeys who needed extra training to reach that level.

So another unique human trait is toppled by Corvids.

Hooray for crows and ravens!

p.s. Not all the scientists agreed with the study’s conclusions. Read more at Scientific American: Crows Perform Yet Another Skill Once Thought Distinctively Human.

(photos from Wikimedia Commons, diagrams by Kate St. John. Click on the caption links to see the originals)

Wild Turkey Fight?

Wild turkey male, strutting (photo from Wikimedia Commons)

23 Nov 2022

Wild turkeys are ancestors of the domestic turkeys we eat on Thanksgiving. Understandably, wild turkeys avoid humans but in rare instances a male becomes aggressive toward people. This happens because turkeys are social birds.

Wild turkey (Meleagris gallopavo) flocks have a social structure called a pecking order that’s especially important during the breeding season in March to May. Dominant males puff and strut and confront other males to maintain their own dominance. If a subordinate gets out of line the dominant turkey struts and gobbles at him, pecks him, or flies at him with spurs exposed. Notice the spur below.

Male wild turkey, focus on the spur (cropped photo from Wikimedia Commons)

A dominant male who is acclimated to people may mistake us as subordinates and try to put us in our place. Occasionally one becomes fixated on bicycles and the cyclists riding them(*).

In one case in Livermore, California an aggressive wild turkey made a motorist’s day. A policeman stopped a speeding driver and was going to issue a ticket but a wild turkey saw the motorcycle and challenged the police officer.

Massachusetts Division of Fisheries and Wildlife has advice on how to prevent wild turkey aggression toward people.

Aggressive behavior towards people occurs when turkeys have become overly comfortable in the presence of humans, usually over several months or even years, in areas where turkeys are fed. [For this reason] Never intentionally leave out food like bird seed or corn in attempts to help or view turkeys.

Spring Tips for Aggressive Turkeys

(*) p.s. I wonder if male turkeys that attack bicycles mistake the wheels for large fanned tail displays.

(photo from Wikimedia Commons, videos embedded from YouTube)