Category Archives: Migration

Population Hit by Bird Flu Recovered in Just 2 Years

Migration, Musings & News, Water and Shore
Barnacle goose closeup (photo from Wikimedia Commons)

9 March 2025

Every autumn barnacle geese (Branta leucopsis) leave their arctic breeding grounds and migrate to Europe. In 2021-2022, those wintering at Solway Firth, UK(*) became infected with highly pathogenic avian influenza (HPAI) H5N1 and 31% of them died. Even though their population had been devastated, they recovered to full strength in just two years. This can give us hope for North American birds hit hard by bird flu.

Wild barnacle geese breed in Greenland, Svalbard and Siberia yet each population has its favorite wintering site as shown on the map. Counts on the wintering grounds are directly tied to one breeding location.

Distribution of barnacle geese highlighting the studied population in 2021-22 (map from Wikimedia Commons)

The winter population at Solway Firth breeds at Svalbard.

Wintering flock of barnacle geese in the fog at Solway Firth (photo from Wikimedia Commons)

When bird flu hit Solway Firth in the winter of 2021-2022 researchers began a two+ year study to measure the demographic impact of the major HPAI outbreak on barnacle geese. During the outbreak they carefully counted dead goose carcasses and, thanks to fencing, were able to extrapolate for predation.

By February 2022 the barnacle goose population had dipped precipitously, but in the two years that followed the number of juveniles increased even faster. High birth rates on the breeding grounds quickly made up for the loss of adults.

Year to year maximum late-winter count of barnacle geese at Solway Firth. From Impacts of highly pathogenic avian influenza (HPAI) on a Barnacle Goose Branta leucopsis population wintering on the Solway Firth, UK

Researchers speculated that …

The large impact of HPAI-related mortality on the Solway Barnacle Goose population was rapidly recovered, probably through a combination of the widespread development of natural immunity and high levels of breeding success in the years following the outbreak.

— Impacts of highly pathogenic avian influenza (HPAI) on a Barnacle Goose Branta leucopsis population wintering on the Solway Firth, UK

In Pennsylvania, snow geese have been hard hit with wild bird flu. It will be interesting to watch how their winter population fluctuates in the eastern U.S. in the years ahead.

p.s. We don’t have barnacle geese in the U.S. Here’s look like.

Barnacle geese (center of photo) look unique but are similar in size to their nearest relative the cackling goose.

One barnacle goose with many cackling geese (photo from Wikimedia Commons)

Size comparison! Though cackling geese look like Canada geese they are much smaller. Thus barnacle geese are smaller than Canada geese we see in Pittsburgh.

Two cackling geese with a Canada goose (photo from Wikimedia Commons)

(*) Solway Firth forms the western border of Scotland and England.

Falconcam Crew Finds a Cache of Cuckoos

Bird Behavior, Migration, Peregrines
Pileated woodpecker skull from Pitt peregrine cache area, 10 Jan 2025 (photo by Kate St. John)

11 January 2025

Yesterday the Univ of Pittsburgh, the National Aviary, and I prepared for the upcoming peregrine nesting season by cleaning the nestbox and falconcams.

After examining the indoor side of the camera equipment Bob Mulvihill of the National Aviary and Gracie Jane Gollinger from Pitt IT braved 10°F weather on the ledge. Camera cleaning went well despite the cold weather and there was nothing to clean at the nestbox. However …

Bob Mulvihill and Gracie Jane Gollinger traverse the ledge, 10 Jan 2025 (photo by Kate St. John)
Bob Mulvihill cleans the snapshot camera, 10 Jan 2025 (photo by Gracie Jane Gollinger)

When Bob stepped out on the landing that leads to the cameras, we were amazed that the area at his feet was strewn with partially eaten prey. I kept a list. Some were hard to identify.

  • Rock Pigeon (Feral) 1
  • Yellow-billed Cuckoo 3 or 4
  • Black-billed Cuckoo 1
  • Pileated Woodpecker 1
  • Northern Flicker 1 (yellow feathers)
  • European Starling 1
  • Wood Thrush 2 or 3

Up to 5 cuckoos! The landing was clean when the chicks were banded on 21 May 2024 so the cache was left since then.

Bob stands among dehydrated peregrine prey: 2 yellow-billed cuckoos and a northern flicker (photo by Kate St. John)
More peregrine prey on the landing, 10 Jan 2025 (photo by Kate St. John)

The most interesting find was the skull of a pileated woodpecker. I assumed that peregrines would never capture a bird with such a dangerous beak but I was wrong.

Pileated woodpecker skull from Pitt peregrine cache area, handheld for scale, 10 Jan 2025 (photo by Kate St. John)
Female pileated woodpecker skull from peregrine cache area, found 10 Jan 2025 (photo by Kate St. John)

Why so many prey items at this spot? Perhaps it was a favorite dining area where the adults dropped off food for last year’s youngsters.

Why so many cuckoos? The Pitt peregrines have always had a fondness for cuckoos, probably because their flight is floppy which makes them easy to catch. My only regret is that the peregrines caught so many cuckoos and wood thrushes.

Here’s the crew after our successful visit.

Left to right: Dante Bongiorni (Pitt Facilities Mgmt), Bob Mulvihill (National Aviary), Doug Cunzolo (Bob assist), Gracie Jane Gollinger (with hat, Pitt IT), Megan Hinds (National Aviary), Kate St. John (“The Peregrine Lady”) — photo by Gracie Jane Gollinger

We’re ready for Peregrine Season!

Just a Few Rare Geese

Climate Change, Migration, Water and Shore
Greater white-fronted geese (photo from Wikimedia Commons)

23 December 2024

It seems that Pittsburgh missed waterfowl migration this fall with only a handful of the expected migrants landing on our rivers and lakes. Except for long distance migrants, waterfowl haven’t come at all.

Some ducks, geese and gulls only move south when ice overtakes their location. If they’re hanging out at Lake Erie near Presque Isle, the map of yesterday’s water temperature indicates they have no reason to leave. The water there is more than 40°F and the only ice is in small bays (black color on the map).

Great Lakes surface Temperature and ice cover as of 22 Dec 2024 (map from Great Lakes Environmental Research Lab)

There are a few rare geese, though, photographed and posted to eBird and embedded below.

There’s currently a Ross’s goose (Anser rossii) at North Park, noticeably small than the Canada geese it’s hanging out with.

Yesterday there was a brant (Branta bernicla) at Duck Hollow without any Canada geese to keep it company. So it hung out with ring-billed gulls.

And a flock of 16 greater white-fronted geese (Anser albifrons) who normally migrate west of the Mississippi and winter in Louisiana, southern Texas and Mexico have been hanging out with Canada geese in Butler County since 1 December.

These geese are called “white-fronted” because their foreheads are white.

Wondering why the ducks aren’t here? This 2021 vintage article explains why.

Why Aren’t The Ducks Here Yet?

Older Is Wiser On Migration

Bird Behavior, Migration
White stork in flight, Huelva, Spain (photo from Wikimedia Commons)

30 October 2024

A long term study of white storks (Ciconia ciconia) in Germany and Austria discovered they improve their migration routes year after year as they gain experience. Older is wiser when it comes to migration.

White storks on migration at La Janda, Spain (photo from Wikimedia Commons)

Back in 2013 researchers fitted more than 250 juvenile white storks with tracking devices that followed each bird as it traveled to its wintering and breeding grounds. As the individuals aged they learned shortcuts, used more direct routes, and moved faster in Spring even though it used more energy.

This graph from the PNAS study Learning shapes the development of migratory behavior shows how the storks’ efforts changed over time.

The influence of age on migration duration for white storks (Ciconia ciconia) that were born in southern Germany and tracked continuously from early life onward. — from “Learning shapes the development of migratory behavior” at PNAS

White storks mate for life and set up housekeeping at age 3 or 4. On the graph we can see that older birds — mated adults — were in a rush to get home but young birds with no nest to reclaim spent time dawdling and exploring.

White stork in flight, France (photo from Wikimedia Commons)

With age comes experience and changing priorities.

Older is wiser … and more driven.

Peregrine Caught Him at 10,000 Feet

Bird Behavior, Migration, Peregrines
Peregrine on the hunt, May 2022 (photo by Chad+Chris Saladin)

27 October 2024

This week the New York Times described A Feathered Murder Mystery at 10,000 Feet which I cannot resist retelling because peregrines are involved. My story will be in photos none of which are from the real episode. See actual photos and the full story at the link above.

In early 2023 scientists from the University of Amsterdam attached satellite trackers to eight black-bellied plovers that were wintering in the Netherlands (a.k.a. grey plovers, Pluvialis squatarola). The goal was to find out where they breed in the Arctic. Here’s what one looks like in spring.

Black-bellied plover in breeding plumage (photo from Wikimedia Commons)

In late May 2023 the birds were migrating northwest over Sweden at almost 10,000 feet when one of them abruptly changed direction 180 degrees, descended to near sea level and completely stopped moving. When a tracking device sends that kind of news, the bird is dead.

Black-bellied plovers in flight in August (photo from Wikimedia Commons)

The scientists, led by Dr. M.P. (Chiel) Boom, went to Sweden to retrieve the tracker and found it on a ledge in an old quarry.

Old abandoned granite quarry, Rixö, Sweden (photo from Wikimedia Commons)

650 feet away from the abandoned tracker was a peregrine nest. (Chances are very good that the scientists did NOT visit during nesting season but the whitewash left on a cliff is a clear indication of who was there in late May.)

Peregrine near nest on Castle Cliff, UK (photo from Wikimedia Commons)

The plover died during peregrine breeding season when there were probably young peregrines in the nest so the father bird went hunting high above where the food was flying.

It’s not a surprise that plovers fly so high — some species fly even higher on migration — but it is a surprise that peregrines hunt at 10,000 feet. The plover’s tracker provided the first documented evidence.

Just when we think we know everything about peregrines, they surprise us again.

p.s. Please keep in mind that none of these photos are from the actual event!

Do Spotted Lanternflies Taste Good? Yes, Says a Vireo

Bird Behavior, Insects, Migration, Spotted Lanternflies
Blue-headed vireo eating insect in Missouri (photo from Wikimedia Commons)

25 October 2024

This week a migrating blue-headed vireo visiting New York City decided that spotted lanternflies taste pretty good.

If you don’t see the video above, click here: pic.twitter.com/t41vaByIp9

Though the current distribution of spotted lanternflies overlaps part of the blue headed vireo’s breeding range, an individual vireo might never have seen a lanternfly before he reached Central Park. This particular bird might be taking his first taste.

Spotted lanternflies at Herrs Island, Pittsburgh, 3 August 2024 (photo by Kate St. John)

How can a blue-headed vireo be naive about spotted lanternflies? It’s easy if he hatched this year. Let’s compare three maps.

1. This map of spotted lanternfly (Lycorma delicatula) distribution shows there are no lanternflies in the Adirondacks, Vermont, New Hampshire. Nor are they in Canada yet.

Spotted lanternfly U.S. distribution as of 12 Sep 2024 (map by Cornell CALS via New York State Integrated Pest Management)

2. Blue-headed vireos (Vireo solitarius) breeding north of NYC nest in Canada, New England and New York state. The vast majority of hatch year blue-headed vireos were born north or outside of the lanternfly’s distribution.

Range map of blue-headed vireo (from Wikimedia Commons)

3. Were these naive birds in Central Park this week? This eBird slideshow of blue-headed vireo abundance for the weeks of 18 and 25 October shows that most vireos have left Canada and are moving rapidly out of New York and New England. The bird in Central Park on 22 October was probably born outside the spotted lanternfly zone.

slideshow of blue-headed vireo abundance from eBird Status and Trends

By now blue-headed vireos have already left southwestern PA and this week they’ll depart from eastern Pennsylvania. Their help with spotted lanternflies will have to wait until next year.

Birds Coming and Going

Migration
Nashville warbler, Frick Park, 20 Oct 2024 (photo by Charity Kheshgi)

23 October 2024

During fall migration birds are coming and going all the time. Some shorebirds pass through in August, September is warbler season, October is sparrow season, and November should be ducks. When we saw a Nashville warbler in Frick Park last Sunday, eBird squawked “That species has left already. Your bird is Rare! You have to justify it.”

In autumn Nashville warblers arrive in southwestern PA during the first week of September and are completely gone by 18 October. Charity Kheshgi’s photo on 20 October is proof that one still lingered.

Swainson’s thrushes have already come and gone, 13 September to 11 October

Remember when we saw a lot of Swainson’s thrushes a couple of weeks ago? Well, they breed in Canada and only visit the Pittsburgh area briefly on migration, approximately 13 September to 11 October (see the map animation).

Swainson’s Thrush (photo by Chuck Tague)
Swainson’s thrush weekly abundance throughout its range (animation from eBird)
Leaving soon: ruby-crowns, chipping and yellow-rumps will be (mostly) gone by 8 November.

This month we’re enjoying ruby-crowned kinglets, chipping sparrows and yellow-rumped warblers but eBird’s weekly abundance maps show that, except for stragglers, these three will leave southwestern Pennsylvania by 8 November. That’s why I was amazed the first time I saw ruby-crowned kinglets overwintering in eastern PA.

Ruby-crowned kinglet, Frick Park, 20 Oct 2024 (photo by Charity Kheshgi)
Chipping sparrow, Oct 2012 (photo by Steve Gosser)
Yellow-rumped warbler eating poison ivy berries in 2013 (photo by Cris Hamilton)
Here until 29 November:

Except for a few stragglers, most red-winged blackbirds will leave southwestern PA by the end of November. If you’re desperate to see one in the winter, visit northeastern Ohio near Akron.

Red-winged blackbirds foraging on the surface of a pond (photo from Wikimedia Commons)
Golden-crowned kinglets, white-throated sparrows and dark-eyed juncos are winter birds.

According to eBird’s weekly abundance maps:

  • Golden-crowned kinglets arrive by 4 October and leave by 26 April.
  • White-throated sparrows arrive around 1 October and leave in the first two weeks of May.
  • Dark-eyed juncos get here 25 October and leave by 26 April. (I’ve seen a few already.)
Golden-crowned kinglet, Frick Park, 7 Nov 2023 (photo by Charity Kheshgi)
White-throated sparrow, white-striped color morph (photo from Wikimedia Commons)
Dark-eyed junco (photo by Cris Hamilton)

Watch dark-eyed juncos come and go in this eBird weekly animation.

Dark-eyed junco weekly abundance map (animation by eBird)

Which Birds Will Visit This Winter?

Migration
Two evening grosbeaks in flight, western Washington State (photo from Wikimedia Commons)

14 October 2024

When North Americans go south for the winter they do it to escape the cold. When boreal finches leave Canada in autumn it’s not about cold, it’s about food.

Winter finches are cold hardy and could stay up north all year but when seed cones and fruit are in short supply they fly south to find food. Every year the Finch Network examines finch food crops across Canada and predicts southward movement by species. Their 2024-25 Winter Finch Forecast came out in late September, summarized below.

This winter we will NOT see these species.

  • Pine grosbeaks (Never come to southwestern PA anyway.)
  • Redpolls
  • White-winged crossbills
  • Red crossbills
  • Redpolls (It feels like a very long time since redpolls came to PA.)
  • Bohemian waxwings (Never come to southwestern PA anyway.)

But we may see …

Purple finch (Haemorhous purpureus)

Purple finch (photo by Chuck Tague)

This year, the majority should leave Canada with a likely moderate flight to the Great Plains and southern United States. … At feeders, they prefer black oil sunflower seeds.

— 2024-25 Winter Finch Forecast

Pine siskin (Spinus pinus)

Pine siskin in Quebec province (photo from Wikimedia Commons)

Areas from Manitoba eastward affected by Spruce Budworm infestations have a poor cone crop. Siskins that bred in these areas will be on the move. While band recoveries show siskins will move straight across North America from coast to coast, there should be some small movement south in the eastern half of the United States this fall in search of food. 

— 2024-25 Winter Finch Forecast

Evening grosbeak (Coccothraustes vespertinus)

Evening grosbeak, January 2013 (photo by Steve Gosser)

Spruce budworms caused problems with the cone crop this summer but there were lots of berries. However, the berries gone now so…

Evening Grosbeaks should visit areas from the Maritime provinces south towards Pennsylvania. Areas even further south to the mid-Atlantic states may see grosbeaks this winter.

— 2024-25 Winter Finch Forecast

These species are not finches, but are part of the prediction.

Red-breasted nuthatch (Sitta canadensis)

Red-breasted nuthatch (photo by Chuck Tague)

Because of patchy balsam fir cones, there should be a moderate to strong flight of red-breasted nuthatches into the U.S.

Blue jay (Cyanocitta cristata)

Blue jay at Frick Park (photo by Charity Kheshgi)

In eastern North America westward to Manitoba the deciduous tree crop (they love acorns on oaks) appears below average with scattered areas of average crops, so expect a moderate to strong flight this fall. 

— 2024-25 Winter Finch Forecast

I’ve already seen lots of blue jays passing through!

Tick Season Returns — On Birds

Insects, Migration
Connecticut warbler banded at Hays Woods with engorged tick above eyering, 8 October 2024 (photo by Nick Liadis, Bird Lab)

9 October 2024

Yesterday while Bird Lab was at Hays Woods, Nick Liadis captured and banded a Connecticut warbler! I was not there to see this rare bird (alas) but Nick sent me a photo. Notice that the warbler has an engorged tick at top right of his eye-ring.

Tick season has returned with a vengeance after a low period during August and September’s drought. Because they cannot live without moisture ticks hang out in humid vegetation, but there was very little available during the drought. All that has changed with the recent rains and black-legged ticks are now active for their mating season which they conduct on the bodies of deer. I was reminded of this yesterday when I saw a deer in Schenley Park with three engorged ticks on its face. (Ewwww!)

Birds that forage on the ground are likely to encounter ticks so its no surprise that the Connecticut warbler and this song sparrow acquired them.

Song sparrow with engorged tick below its eye
(photo from Scott, & Clark, Kerry & Coble, & Ballantyne,. (2019). Detection and Transstadial Passage of Babesia Species and Borrelia burgdorferi Sensu Lato in Ticks Collected from Avian and Mammalian Hosts in Canada. Healthcare. 7. 155. 10.3390/healthcare7040155)

Birds, in fact, are an integral part of the tick’s life cycle. Notice the robin in the Summer section of the CDC diagram below.

Black-legged tick life cycle (diagram from CDC enhanced with lifeform names)

I used to say that deer were the black-legged ticks’ long distance transport system but I’ve changed my mind. It’s birds. A 2015 study found that 3.56% of the songbirds migrating north into Texas in the spring are carrying tick(s), most of which are native to Central and South America.

The bird-tick transport system works both ways. A 2019 tick-host-pathogen study in Canada found that some birds carry ticks with pathogens on fall migration.

Poor birds! They need all the strength they can get to complete their migration. It doesn’t help when ticks are sucking their blood.

Meanwhile, be careful about ticks out there! Lyme disease, transmitted by ticks, is terrible. Check your clothing while you’re in the field and thoroughly check your body for ticks when you return home. Click here for ways to prevent infection by keeping ticks off your clothes and body.

p.s. Support Nick Liadis’ efforts with a donation at Bird Lab’s GoFundMe site.

Visiting Birds Find New Insect Snacks

Bird Behavior, Migration
Immature yellow-bellied sapsucker near spotted lanternflies, Frick Park, 6 Oct 2024 (photo by Charity Kheshgi)

8 October 2024

Bird migration was intense over Pittsburgh on Friday night, 4 October, when more than 20,000 songbirds flew south overhead. We saw the results on Saturday morning in Frick Park where a new cohort of species had arrived with good news: Some of them were eating spotted lanternflies!

The new species included ruby-crowned kinglets, white-throated sparrows, yellow-bellied sapsuckers and yellow-rumped (myrtle) warblers. The mix was quite a change from September’s warblers.

Most of the new arrivals were feeding on tiny insects but the juvenile sapsucker, pictured above, was attracted to sweet lanternfly honeydew on ailanthus trees. He was too young to have ever seen a spotted lanternfly but he was curious. “Are these edible?”

Immature yellow-bellied sapsucker looking at spotted lanternflies, Frick Park, 6 Oct 2024 (photo by Charity Kheshgi)

Yes.

Perhaps the sapsucker got the idea from a northern cardinal that ate a lanternfly further down the trail. (I don’t have a photo of that incident; this one is from iNaturalist, New York.)

Northern cardinal eating spotted lanternfly, NYC (Creative Commons photo by
matthew_wills via iNaturalist)

Olive-sided flycatchers eat spotted lanternflies, too, though they don’t contribute much in Pittsburgh because they are rare here.

Olive-sided flycatcher (photo from Wikimedia Commons)

However, when an olive-sided flycatcher was passing through Howard County, Maryland in early September Mei Shyong photographed it eating a spotted lanternfly. The thumbnail below is just a hint. Click here or on the image to see her photo at Howard County Concervancy on Facebook.