Category Archives: Bird Behavior

Landscape of Fear

Adult Cooper’s hawk (photo by Dave Brooke)

8 September 2021

Fear causes an inability to thrive in humans. Now a new study shows this is true of birds as well.

As a grad student at University of Massachusetts in Amherst, Aaron Grade decided to parse out why urban nestlings are lower weight than their rural cousins. It’s well known that urban settings have poor habitat, altered food sources and more predators but the likelihood of predation is lower there because urban predators have so many other food choices.

House wren at nestbox (photo from Wikimedia Commons)

Grade wondered if fear play a role so he set out 38 house wren nest boxes and loudspeakers in participants’ backyards in urban, suburban and rural western Massachusetts. During the nesting season participants played back the sounds of two predators of house wrens: Cooper’s hawks (pictured at top) and eastern screech-owls (below).

Eastern screech-owl (photo by Bobby Greene)

Though there was no actual danger, parent house wrens responded to the sounds by guarding their young and perhaps feeding them less. In the end nestlings in these playback settings were 10% underweight no matter what habitat they grew up in.

The study found that whether the birds are hurt or not, their nestlings are underweight and less likely to survive if the family lives in fear.

“These landscapes of fear,” says Grade, “can have a greater effect on behavior and survival than the actual predator itself.”

Science Daily: How landscapes of fear affect the songbirds in our backyards

Birds and humans cannot thrive in constant fear.

Read more about the birds at Science Daily.

Read about humans at Low Birth Weight Babies and Black Women: What’s the Connection?

(photos by Dave Brooke, Wikimedia Commons and Bobby Greene)

p.s. This is also a lesson for birders: Avoid using playback of predator sounds, especially during the spring and summer nesting season!

What do Ospreys have in common with Golden Retrievers?

Golden retriever at the beach (photo from Wikimedia Commons)

31 August 2021

When dogs get wet they shake it off.

So do ospreys.

It’s a bit trickier to shake off in the air.

(photo from Wikimedia Commons, video embedded from YouTube, tweet embedded from @marktakesphoto)

Hummingbirds Are Rowing in the Sky

Anna’s hummingbird at UC Berkeley Botanical Garden, 2018 (photo from Wikimedia Commons)

25 August 2021

Hummingbirds hover and zip, levitate and fly backwards. How do they do it?

At more than 50 beats per second(*) their wings are so fast that we can’t see what they’re doing so UC Berkeley captured and filmed Anna’s hummingbirds in high-res video.

Played back in slow motion we see their wings moving forward and back in a figure 8 like oars in a boat. Hummingbirds are rowing in the sky!

Check out this PBS Deep Look.

(*) The fastest recorded wing beats were 80 beats per second by an amethyst wood-star hummingbird.

(photo from Wikimedia Commons; click on the caption to see the original, video embedded from PBS Deep Look)

A Little Pair Bonding

Morela preens at the green perch, 12:24pm 12 August 2021 (photo from the National Aviary snapshot camera)

15 August 2021

Mid-August is a quiet time for the Cathedral of Learning peregrine falcons. This year’s youngsters have left the area to begin their life adventures while the adults stay close to home and wrap up their annual molt.

Morela and Ecco rarely visited the nestbox in July but last Thursday 12 August they spent eight minutes bowing together. They were not courting. They were strengthening their pair bond.

In other news, I usually don’t check the snapshot camera but when I did so on Monday 9 August at 4:44am Morela was perched there in the dark. This was a one-time event.

Morela before dawn, 4:44am, 9 August 2021 (photo from the National Aviary snapshot camera at Univ of Pittsburgh)

To check the snapshot camera scroll down on this webpage to see the 2nd image. NOTE: The first image is the streaming camera which is not functioning now.

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

When Hummingbirds Refuel

Anna’s hummingbird, California (photo by Terry Lucas via Wikimedia Commons)

11 August 2021

When hummingbirds sip nectar it can change their external body temperature. The change is visible in this thermal video of an Anna’s hummingbird by Gary Nunn.

I’ve highlighted the bird’s temperature change with a slideshow of before and after snapshots.

  • Before feeding: The bird’s head, body and throat are hot red. His shoulders are cool green.
  • After feeding: The bird’s crop is full of cool nectar so his throat turns yellow. His shoulders warm up from green to yellow.

If we had a thermal sensor we could watch these Anna’s hummingbirds change color as they refuel.

(photo from Wikimedia Commons, embedded Tweet and YouTube; click the captions/logos to see the originals)

Who Is The King of Birds?

Bald eagle, female at Hays, 24 July 2021 (photo by Theo Lodge)

2 August 2021

Many would say the bald eagle is the king of birds but when it comes to attitude, actions and name the small songbird attacking this eagle is both King and Tyrant.

Eastern kingbird attacks bald eagle, Hays, 24 July 2021 (photo by Theo Lodge)

Attitude: The eastern kingbird is often fierce and angry. This one is showing the orange-red crest he keeps hidden beneath his head feathers until he’s very, very mad.

Eastern kingbird (photo by Andy Reago and Chrissy McClarren from Wikimedia Commons)

Actions: Eastern kingbirds relentlessly defend their territories and will (obviously) ride the backs of hawks and eagles to peck their heads. 

Males and sometimes females are very aggressive in territorial disputes [with other kingbirds], often resorting to aerial fights in which they lock feet together, pull out each other’s feathers, and sometimes fall to the ground. Eastern Kingbirds also attack large nest predators like crows and Blue Jays. Such aggression has been shown to increase their breeding success.

from Eastern Kingbird account, All About Birds

In late July when Theo Lodge took the attack photo, the kingbird was ensuring a successful breeding season by defending his “kids.” The juveniles look like adults now except for yellow mouths.

Juvenile eastern kingbird, 23 July 2013 (photo from Wikimedia Commons)

And so the eastern kingbird earned the common name of king and a scientific name, Tyrannus tyrannus, that doubles up on tyrant.

Enjoy them now in Pittsburgh. They’ll be gone by early September.

(eagle photos by Theo Lodge, kingbird photos from Wikimedia Commons)

A Little Pair Bonding

18 July 2021

This spring Ecco and Morela successfully raised four young peregrines at the Cathedral of Learning. All four fledged in early June and became independent in the subsequent weeks. One or two stopped by for a handout in early July but Ecco and Morela were having none of it. “You’re on your own.”

Now that the “kids” are gone (wrong! see below), Ecco and Morela are molting and staying close to home. In the past two days they have visited the nest several times and bowed together for a little pair bonding.

p.s. In the slide with Morela’s open wings, notice that she is replacing her middle two tail feathers. The white tips are halfway down her tail.

UPDATE 18 July 2021 at 5pm: The “kids” aren’t all gone. One of the youngsters was circling and begging loudly at 5pm at the Cathedral of Learning.

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

July Is Goldfinch Month

American goldfinch (photo by Chuck Tague)

12 July 2021

While most songbirds began nesting in May and some have finished for the year goldfinches wait until now to start a family.

Unlike most birds American goldfinches (Spinus tristis) are totally vegetarian. They eat only plant matter, never insects, worms or meat so they wait to nest in July when their favorite foods are plentiful. Foods such as thistle seed.

Male American goldfinch on thistle (photo from Wikimedia Commons)

The female goldfinch builds her nest in a shrub or sapling, laying a foundation of spider silk and adding rootlets and fibers. Then she lines the nest with soft down, often using thistle fluff.

Female American goldfinch in July (photo from Wikimedia Commons)

She lays one egg per day for a clutch of five and starts incubation at the next-to-last egg. In 12-14 days her babies hatch.

American goldfinch nest with young (photo by Chuck Tague)

It’s still July. Now the fun begins!

The parents make many trips back and forth from thistle fields to the nest where they feed by regurgitation. Sometimes the adults munch on leafy vegetables, even in gardens, which earned them the nickname “Salad Birds.”

If the nest had a cowbird egg in it that brown-headed cowbird nestling dies within 3 days because it can’t survive without insect protein.

Meanwhile if you listen for the male in his looping courtship flight you might be able to find the nest inside his circle. Listen and watch for “potato chip.”

You’ll also hear a new call if anything dangerous shows up near the young. The warning is “beer BEE.”

While scarlet tanagers, Baltimore orioles and northern rough-winged swallows have finished nesting, July is goldfinch month.

(photos by Chuck Tague and from Wikimedia Commons; click on the caption to see the original)

Don’t Worry, I’m Sunning

25 June 2021

On Wednesday Bob Donnan emailed me with photos of a tufted titmouse in a very odd posture: “Noticed a bird on the roof of our shed doing this just before lunch. … It seemed fine, since it flew away within a minute after I took these photos.”

On sunny hot days you may see a bird perched or lying flat like this titmouse with its wings spread, feathers fluffed, beak open, and one side of its face turned to the sky. This bird is sunbathing.

For birds sunbathing is more than just warmth and relaxation. Studies have found that the heat kills lice or forces the parasites to move to areas the bird can reach while preening.

This 8-minute video by Lesley the Bird Nerd shows odd postures that birds take while sunning and lists reasons why they do it. I’ve summarized her list below her video in order of importance.

Birds sunbathe …

  1. To rid their feathers of parasites:
    • heat kills lice
    • heat makes parasites move to areas easier to reach while preening
  2. To dry off after bathing or rain
  3. To warm up on cold days (For example: turkey vultures on cold mornings)
  4. For vitamin D
  5. For enjoyment and relaxation

So if you see a bird doing this don’t worry, he’s sunning.

For more information see Hot, Bothered and Parasite Free: Why Birds Sun Themselves.

(photos by Bob Donnan, video from LesleyTheBirdNerd)