Category Archives: Bird Behavior

Peregrines Are Just Tiring Them Out

Bird Behavior, Peregrines, Water and Shore
Peregrine falcon looking for a meal (photo from Wikimedia Commons)

13 October 2023

When peregrine falcons migrate down the Pacific Coast in autumn they often pause at Canada’s Fraser River Delta to hunt shorebirds. Pacificnorthwestkate (@pnwkate) filmed one working a sandpiper flock at Roberts Bank.

Peregrines on the hunt hope to separate a single bird from the crowd because they cannot catch anything in such a tight flock. When a lone bird can’t keep up it becomes the peregrine’s dinner.

Flock of dunlin (photo from Wikimedia Commons)

Dunlin flocking behavior on the Pacific Coast changed after the peregrine population recovered in the 1990s. A study at the Fraser River Delta in 2009 found that dunlin quickly learned it was unsafe to roost at high tide during the day because peregrines were on patrol. Instead they began to spend high tide flocking over the open ocean, flying continuously for three to five hours.

A new study, published this month in Phys.org, looked at the interaction from the peregrines’ perspective and found that the falcons haze the dunlin flocks to keep them moving. Peregrine hunting success improved at the end of those 3-5 hours of continuous flying because the dunlin had to stop for a rest.

The hunting data showed that dunlins were at greatest risk of predation just before and just after high tide, and spent most of the riskiest period flocking. However, there was a sharp increase in kills two hours after high tide, because the dunlins were not flocking despite elevated risk. [They were resting.]

— phys.org: Peregrine falcons set off false alarms to make prey easier to catch, study finds

So the dunlin changed their behavior to avoid peregrine predation and the peregrines changed their behavior to wear out the dunlin. Peregrines have more stamina that dunlin.

Read more about the peregrines’ hunting strategy at Phys.org: Peregrine falcons set off false alarms to make prey easier to catch, study finds.

(credits and links are in the captions)

Birds Near Naples Are Flying More Than Usual

Bird Behavior, Musings & News
Rock pigeons in flight (photo from Wikimedia Commons)

12 October 2023

West of Naples, Italy there’s an area called Campi Flegrei (Phlegraean Fields) that contains the remains of a ruptured supervolcano. It has erupted many times over the past 315,000 years including an eruption 40,000 years ago that produced a huge ash cloud and may have driven the Neanderthals to extinction.

The region around the Gulf of Naples is very volcanic. There are vents at Solfatara in Pozzuoli where sulfurous steam emerges in an old crater. Pompeii and Vesuvius are across the Gulf.

Sulfur vents at Solfatara, Pozzuoli, Italy (photo from Wikimedia Commons)

Nonetheless it’s a lovely place to live by the Mediterranean. Towns, including Pozzuoli, Agnano and Bacoli, dot the crater edges and the flats between them. The area’s population is 500,000.

Scene from Pozzuoli, Italy (photo from Wikimedia Commons)

This slideshow of maps shows the towns among the remnants of the supervolcano.

In June 2023 scientists determined that there is a potential for rupture before an eruption at Campi Flegrei caldera, Southern Italy. (uh oh!)

In September the magma under Campi Flegrei began shifting again and caused more than 1,100 earthquakes in a month, some as strong as 4.0 and 4.2 on the Richter scale. The Guardian reported on 3 October: “The Italian government is planning for a possible mass evacuation of tens of thousands of people who live around the Campi Flegrei supervolcano near Naples.”

Years ago I learned that birds can sense when an earthquake is coming and they take flight before it hits. I suspect that the birds at Campi Flegrei are flying more than usual lately.

Read more about birds and earthquakes in this vintage article from 2016.

Birds Take Flight Before Earthquake

(photos from Wikimedia Commons, click on the captions to see the originals. Map credits: colorful relief map from Wikimedia, Fig. 1 map: Unrest at Campi Flegrei since 1950 from Potential for rupture before eruption at Campi Flegrei caldera, Southern Italy published June 2023 at Nature.com, Google map of the area with terrain)

Leave The Leaves

Bird Behavior, Songbirds
Woolly bear, Isabella Tiger Moth caterpillar, 3 Oct 2018 (photo by Kate St. John)

6 October 2023

In October we see woolly bear caterpillars (Pyrrharctia isabella) out in the open, crossing the trails. Because they overwinter as caterpillars, they’re busy looking for the perfect place to spend the winter in leaf litter, under bark or beneath a fallen log.

Fallen leaves in Schenley Park, Nov 2016 (photo by Kate St. John)

Leaf litter is key winter habitat for a lot of insects including springtails, millipedes, earthworms, butterflies and moths.

Millipede(*) Hays Woods, Sept 2023 (photo by Kate St. John)

It also shelters salamanders and newts …

Red eft among the leaf litter in West Virginia (photo from Wikimedia Commons)

… and provides an insect hunting ground for birds including eastern towhees, dark-eyed juncos, robins and mockingbirds.

Eastern towhee, male (photo from Wikimedia Commons)

If you’ve been thinking about “wilding” your yard — even just a little bit — now is a great time to start. Leave the leaves. You don’t have to leave it messy. Here’s advice on what to do.

Leaving the leaves and other plant debris doesn’t have to mean sacrificing your yard to the wilderness. The leaves don’t need to be left exactly where they fall. You can rake them into garden beds, around tree bases, or into other designated areas. Too many leaves can kill grass, but in soil they can suppress weeds, retain moisture, and boost nutrition. 

Avoid shredding leaves with a mower. Raking or blowing are alternatives that will keep leaves whole for the best cover and protect the insects and eggs already living there.

If you decide you need to clean up the leaves and debris in spring, make sure you wait until late in the season so as not to destroy all the life you’ve worked to protect. 

— Xerxes Society: Leave the Leaves: Winter Habitat Protection

Take a break this weekend. Don’t bag those leaves! Just push them aside for wildlife. 🙂

(photos by Kate St. John and from Wikimedia Commons)

(*) p.s. The millipede was easy to photograph because it was dead, probably the victim of a parasitic fungus that prompts the millipede to climb high on a twig before it dies. I wrote down the name of the fungus when I took the picture but cannot read my writing. Perhaps it’s Anthrophaga myriapodia.

Do Blackpolls Sleep in Flight Over the Atlantic?

Bird Anatomy, Bird Behavior, Migration
Blackpoll warbler in PA, Oct 2020 (photo from Wikimedia Commons)

5 October 2023

Some birds are champion fliers, staying airborne for days or months at a time. Scientists wondered if birds sleep in flight and proved that they do in a 2016 study of great frigatebirds, finding that the birds either “sleep with one half of their brains active, or with both hemispheres shut down at the same time.” Read more in this vintage article, Asleep in Flight.

Blackpoll warblers (Setophaga striata) are also champion fliers making a non-stop fall migration over the Atlantic Ocean of 1,900 miles in 72 to 88 hours. Traveling at 27 mph, they launch from the east coast between Nova Scotia and South Carolina and fly to their only stopover in Puerto Rico or Hispaniola (Haiti & Dominican Republic), then on to northern South America.

The blackpoll’s transoceanic path was proven in a 2015 study by Bill DeLuca and the Vermont Center for Ecostudies. VCE writes:

Bill DeLuca (Northeast Climate Science Center) and VCE solved this great modern-day avian mystery. Using light-level geolocators attached to Blackpoll Warblers in Vermont and Nova Scotia, DeLuca and colleagues documented the longest distance non-stop overwater flights ever recorded for a migratory songbird. During October, Blackpoll Warblers initiate a ~3-day non-stop transoceanic flight of ~2500 km from the north Atlantic Coast to Hispaniola and Puerto Rico. Radar data show migrating songbirds fly at 2,600 to 20,000 feet while making this journey. After a few weeks, they fly onto Columbia or Venezuela where they overwinter. Their spring migration route takes them over Cuba to Florida, where they journey up the eastern US seaboard to reach their breeding grounds in late May.

— Vermont Center for Ecostudies: Blackpoll Warbler

Notice in this eBird abundance map for the week of 2 Nov that blackpolls are:

  • bunched up on the East Coast from Massachusetts to North Carolina
  • at a stopover on Puerto Rico and
  • early migrants have already arrived in South America.
Blackpoll warbler weekly abundance map, week of 2 Nov 2007-2021 (map from eBird Status and Trends)

Watch them throughout the year in this eBird abundance animation.

Blackpoll warbler weekly abundance map (animation from eBird Status and Trends)

Of course I wondered if blackpoll warblers sleep in flight during their 3 day transoceanic trip, but we won’t find out any time soon. Blackpolls are way too small to wear the sleep monitoring gear used on the great frigatebird.

(photo from Wikimedia Commons, maps from eBird Weekly Abundance; click on the captions to see the originals)

ebird species migration weekly abundance trends

Young Red-Tail Hunts at the Hospital

Bird Behavior, Birds of Prey

28 September 2023

On Saturday 17 September, my friends Mary and Bea were walking to the Bloomfield Saturday Market when they couldn’t help but notice a red-tailed hawk (Buteo jamaicensis) hunting on the lawn at Shadyside Hospital. Mary stopped to take his picture.

Perched on the blue sign, I can tell the bird is immature because his tail isn’t rusty red. In early June he was still in the nest. Soon he learned to fly, then to hunt. Now, months later, he can feed himself but he’s not an expert. It takes time and luck to get a meal.

In autumn young red-tails disperse on their first migration and every place they stop is completely new to them. Those that grew up in urban environments are unbothered by traffic and people so they may gravitate to open areas near buildings in search of prey.

This hawk was so focused on hunting that he ignored Mary while she took his picture. Read more about the hawk’s single mindedness in this article from 2009.

Single-mindedness

p.s. This red-tail may have been attracted to the noise of house sparrows tweeting inside that bright green hedge. There are always lots of them in there, but they shut up as soon as I look so I rarely see one. As far as I know, I’m the only one — other than a hawk — that peers inside that hedge. 😉

(photos by Mary Tuttle)

Juvenile Cooper’s Hawks Learn to Hunt

Bird Behavior, Birds of Prey
Two juvenile Cooper’s hawks in Frick Park, 14 July 2022 (photo by Charity Kheshgi)

22 September 2023

Every year young Cooper’s hawks (Accipiter cooperii) fledge in June/July and learn to hunt in July/August. As soon as they’re self sufficient they disperse, and then they start to migrate.

Cooper’s hawks eat birds for a living so they migrate with their prey. Their peak migration continues now through mid October at the Allegheny Front Hawk Watch.

How did they get to this point? Let’s take a look back to August as some young Cooper’s hawks perfect their hunting techniques in New Jersey. It involves a lot of jumping.

video embedded from PTZtv on YouTube

(credits and links are in the captions)

Peregrines Together in September

Bird Behavior, Peregrines
Ecco watches while Carla preens, 15 Sep 2023, 3:54pm

16 September 2023

Yesterday Ecco and Carla spent lots of time hanging out together at the Pitt peregrine nest. The snapshot camera’s motion detector captured their activity.

Beginning at 3:50pm the pair spent 45 minutes together, bowing, preening, and watching. When Ecco left, Carla continued on the perch for another half hour, then stretched and departed at 5:00pm.

Two minutes later Ecco landed at the exact same spot on the perch. Because female peregrines are larger than males, the switch from Carla to Ecco made it look as if the bird shrank.

Ecco preened for more than an hour, then stretched and vaulted up to leave at 6:13pm. All told, the peregrines were present on camera for nearly 2.5 hours.

This slideshow shows 144 minutes of their interactions in only 1 minute and 15 seconds. If you miss the captions on the first pass, don’t worry, the slideshow repeats.

(photos from the National Aviary snapshot falconcam at Univ of Pittsburgh)

Flamingos Have Been Popping Up All Over

Bird Behavior, Water and Shore, Weather & Sky

3 September 2023

Except for a few rare sightings in Florida, flamingos seen in the U.S. are not from the wild, they’re escapees from a zoo. Then suddenly last week, after Hurricane Idalia, flamingos have been popping up all over.

At top, 16 flamingos visited Fred Howard County Park near Tarpon Springs, FL. Below, 6 flamingos stopped by St. Mark’s National Wildlife Refuge, 30 miles south of Tallahassee.

The groups have often been a mix of pink adults and gray youngsters.

As of Saturday evening the totals were:

  • 100+ in Florida
  • 11 at Pea Island, North Carolina
  • 2 in South Carolina
  • 2 in Virginia
  • 3 in Alabama
  • 5 in Tennessee
  • UPDATE on 4 Sep 2023: 1 in Kentucky
  • and 2 in OHIO! at Caesar Creek State Park. These were seen for only a day and then gone.
  • UPDATE on 7 Sept 2023: 2 flamingos in Franklin County, PA pictured below: First reported on eBird on 7 Sept but apparently present for 2 days prior as well.

American flamingos (Phoenicopterus ruber) are native to the northern shore of South America, the Caribbean islands, Cuba, and the Yucatan in Mexico. Hurricane Idalia plowed through a few of those locations.

Range map of American flamingo (Phoenicopterus ruber) from Wikipedia

This WKRG video on 27 August shows Hurricane Idalia gaining strength as it spans the Caribbean, overlaying part of the Yucatan and all of Cuba. The flamingos would have felt it coming and flown north and northeast to get out of its way. Notice the lower speed winds (shades of green) on the edge of the weather map. The green wind track is where most of the flamingos have been found.

video from WKRG News on YouTube

Considering the storm track, the flamingos are probably from Cuba and the Yucatan including at least one banded bird.

Given all the discussion about the flamingos now appearing all over Florida (and farther north), this eBird list from Amy Grimm is especially relevant. This afternoon, Grimm documented 8 flamingos at Marathon, in the Florida Keys, and noted that “One has large yellow band on the right leg code DXCL, small silver band on left leg.” Do the bands mean it’s escaped from captivity? No. This combination — yellow PVC band on one leg with 4-letter code in black letters, ordinary band on other leg — has been used for years in the ongoing project to band American Flamingos in the big colony at Rio Lagartos, on the north coast of Mexico’s Yucatan Peninsula.

— Kenn Kaufman at ABA Rare Bird Alert Facebook Group

Flamingo sightings will end as the birds head home. For now, enjoy them in videos.

video from Tampa Bay Times on YouTube
video embedded from @10TampaBay on YouTube

(credits are in the captions)

Out of Sight, But Not Out of Mind

Bird Behavior, Peregrines
Ecco and Carla bow at the nest, 31 August 2023, 4:17pm (photo from the National Aviary snapshot camera at Univ of Pittsburgh)

1 September 2023

The National Aviary’s streaming camera is off for the season so the Pitt peregrines are virtually out of sight, but they are not off my mind. Every day I check the Cathedral of Learning’s ledges to see where they’re perched and I look at the snapshot camera in case they’ve been to the nest.

Activity at the nest picked up this week because fall is coming and migration is underway. The length of day is similar to spring and they’re taking an interest in songbird migration as prey flies overhead at night.

Ecco and Carla bowed at the nest three times yesterday, including an extended bowing session, to strengthen their pair bond and their claim on the nest.

All of Pitt’s resident peregrines(*) stay home for the winter and I expect Ecco and Carla to do the same. They don’t need to migrate because there’s plenty of food in the winter (pigeons and starlings) and their “cliff” is too valuable to lose by vacating it for six months.

So I’m still watching. The Pitt peregrines may be out of sight but they are not out of my mind.

(*) There’s a lot of history that allows me to say that. Peregrines have lived at the Cathedral of Learning for 22 years, spanning 8 adult birds.

(photos from the National Aviary snapshot camera at Univ of Pittsburgh)

Sleeping On Migration

Bird Behavior, Migration
Sparrow asleep in New Mexico (photo by Larry Lamsa via Flickr Creative Commons license)

31 August 2023

Migration is exhausting work and since warblers migrate at night, they must rest and refuel during the day. Food and good cover are both essential at their rest stops. Sleeping is a dangerous activity where predators lurk.

A study published in Current Biology, August 2019, revealed one way that migrating warblers manage these dangers and demands: They adjust their sleep postures depending on their physical condition and physiological needs. Plump, well-muscled birds tend to sleep with their heads held upright, while scrawnier warblers tuck their heads into their feathers, a posture that makes them more vulnerable to predation but helps them conserve their much needed energy.

— New York Times: Some Migratory Birds Sleep Better Than Others, August 2019

Fit warblers can afford to be vigilant. They puff up and sleep in a watchful posture, sometimes out in the open. This makes them ready to escape at a moment’s notice.

Sardinian warbler asleep on a branch (photo from Wikimedia Commons)

Exhausted warblers hide in thickets and tuck their heads under their wings. This provides much needed rest and protects against heat loss but makes them vulnerable to predators. Interestingly, these same birds sleep less than those in good condition because they have to spend more time foraging.

Bird sleeping with head tucked under wing (photo from Wikimedia Commons)

Some long distance migrants, such as the ocean-going great frigatebird, can sleep in flight.

Great frigatebird in flight (photo from Wikimedia Commons)

A 2016 study equipped great frigatebirds (Fregata minor) with EEG equipment and proved that they sleep while flying though they get less sleep in the air than on land. Read more in this vintage article.

Asleep In Flight

It would be nice to safely sleep while doing other things. Yawn! I’m ready right now.

(photos from Wikimedia Commons, see links in the captions)