Category Archives: Bird Behavior

How Do Peregrines Increase Accuracy? Fly Faster!

Bird Behavior, Peregrines
Gusto heads into a stoop, 9 Feb 2022 (photo by Chad+Chris Saladin)

3 December 2023

Peregrines are the fastest animal on earth when they dive at 200 mph to catch their prey in flight. In fact they dive even faster when they’re hunting an evasive bird. The higher speed increases turning force so they’re more accurate at catching prey.

In 2005 Ken Franklin went sky diving with a peregrine to clock its maximum freefall speed at 242 mph (389 km/hr).  In 2018 scientists wanted to study the details of the peregrines’ dive, but it was too hard to do in real time, so they created 3D simulations of a stooping peregrine pursuing a European starling.

The simulations showed that optimal speed for catching a bird in straight flight is 93 mph but if the prey is zig-zagging in the sky the best speed is 225 mph.

You’d think that the higher attack speeds would make it more difficult for falcons to adjust to a moving target. But the opposite turned out to be true: The predators were more maneuverable at higher speeds because they could generate more turning force; only then were they able to outmaneuver the highly agile starlings. So stoops don’t just help falcons quickly overtake prey—they also help the predators change directions.

— Science Magazine: Peregrine falcons maneuver best when dive-bombing at more than 300 kilometers per hour

Watch how it works in this video from Science Magazine. You’ll need these equivalents as you watch.

  • 300 km/hr = 186 mph
  • 150 km/hr = 93 mph
  • 360 km/hr = 223+ mph. I rounded up to 225 mph
video from Science Magazine on YouTube

African Penguins Use Dots to Recognize Mates

Bird Behavior, Water and Shore
African penguins at Boulders Beach, South Africa (photo from Wikimedia Commons)

26 November 2023

We humans recognize each other by face and can sometimes recognize individuals in other species as well. For instance, African penguins (Spheniscus demersus) have unique patterns of dots on their chests that zookeepers use to tell them apart. Psychologist Luigi Baciadonna wondered if the dots functioned the same way for the penguins themselves so he ran an experiment at Zoomarine Italia in Rome.

African penguins walking down a ramp at Boulders Beach, South Africa (photo from Wikimedia Commons)

In the experiment individual penguins were herded into a small corral with life-size portraits of two group members, at least one of which was his/her mate. African penguins like to hang out near their mates so if the visiting bird stared at the mate’s portrait and gravitated toward it, he/she was recognizing the mate. The experiment had three variations:

Test #1: Accurate photos: one of the mate, one of another member of the colony. Result: In this video of Test#1 a male penguin, Gerry, is presented with an image of his partner, Fiorella, on the left and one of group member Chicco on the right. Notice what he does.

(video from Science Direct: African penguins utilize their ventral dot patterns for individual recognition)

Test 2: Two photos of the mate: one accurate, one with dots digitally removed. Result: The birds spent more time looking at the mate photo with dots.

Test 3: Dots digitally removed from both photos: mate and another member of the group. Result: The birds no longer seemed to recognize their mate. There was no difference in how long they gazed at the mysteriously spotless portraits.

Quiz! Now that I know African penguins have unique chest dots I discovered that the penguin pictured below is also in a photo above. Which one is he?

African penguin at Boulders Beach, South Africa (photo from Wikimedia Commons)

Visit the National Aviary in Pittsburgh to check out the African penguins’ dotted chests at Penguin Point.

Penguin Point exhibit at the National Aviary in Pittsburgh (photo from the National Aviary)

Read more about the study at Science Direct: African penguins utilize their ventral dot patterns for individual recognition

(credits are in the captions)

Can You Spot the Peregrine?

Bird Behavior, Peregrines, Water and Shore
Stirring up the pigeons in Cleveland, 2017 (photo by Chad+Chris Saladin)

17 November 2023

Can you spot the peregrine?

When peregrines are hungry, the birds they’d like to eat flock tightly and move as fast as they can. The denser the flock the harder it is for the peregrine to pick out a solo bird to catch for dinner.

In the photo above pigeons are flying crosswise to avoid an oncoming peregrine. Can you spot the peregrine in the picture?

Dunlin (Calidris alpina) are masters of tight flocking and evasive maneuvers when threatened from the air. In the video below by Pacificnorthwestkate (@pnwkate) the dunlin move like a murmuration of starlings as a peregrine harasses them. Can you spot the peregrine?

embedded video by Pacificnorthwestkate on YouTube

Notice how the dunlin flock winks off and on in the video, dark at one moment then so white they disappear. In winter plumage dunlin have brown-gray backs and white bellies. The flock changes color as the birds turn in unison in the air.

Dunlin in winter plumage (photo from Wikimedia Common)

Last month I wrote about peregrines’ winter strategy for catching dunlin: Peregrines Are Just Tiring Them Out.

(credits are in the captions)

Caught In The Act

Bird Behavior, Mammals
Great egret chases a cattle egret that’s carrying a mouse (photo by Wendy Miller via Flickr Creative Commons license)

10 November 2023

“Hey!” says the great egret as it chases the cattle egret. “That’s my mouse!”

Cameras capture birds and animals in surprising ways. A stack of shorebirds. A bobcat on a prickly perch.

tweet embedded from @AubertHeidi1
tweet embedded from @AZStateParks

And deer running from …?

In New Jersey a buck ran through a front yard, jumped over two cars, and miscalculated the landing. Despite that he hopped out of the truck bed and ran away.

video embedded from Fox 26Houston

This month deer are still in the rut and still running into traffic. Caught in the act.

(credits are in the captions)

Turning Their Backs On Us

Bird Behavior
Yellow-rumped warbler, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)

5 November 2023

Some days it seems like all the birds are turning their backs on us. Warbler season is especially challenging because they tend to pose just like the yellow-rumped warbler above. Fortunately The Warbler Guide by Tom Stephenson & Scott Whittle includes a butt-shot for every bird so if you take photographs you can look them up when you get home.

Most birds just happen to be facing away but others, like this hermit thrush, do it intentionally. The thrush was keeping an eye on us while he hid in the shadows with an escape route mapped out ahead of him.

Hermit thrush presents his back and keeps an eye on us, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)

Kinglets face every which way as they busily flit to find tiny insects. Inevitably they end up in a butt shot.

Ruby-crowned kinglet, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)

Sometimes we see a new feature of the bird from behind. This golden-crowned kinglet shows a bit of red at the back of his yellow crest …

Golden-crowned kinglet showing a hint of red in his crest, Frick Park, 26 Oct 2023 (photo by Charity Kheshgi)

… as seen in this closeup.

Closeup of golden-crowned kinglet’s head with hint of red in his crest (photo by Charity Kheshgi)

Surprisingly, some sparrows have faces on their back ends as seen in Wes Iversen’s photo of a fluffed up sparrow. Notice how the secondary wing feathers, back, and undertail coverts form eyes, nose and smiling mouth. The photograph is embedded from Wes Iversen’s original here on Flickr.

Bird Butt
The face on the back end of the bird. Fluffed sparrow from behind (embedded photo by Wes Iversen on Flickr)

Check out more of Charity Kheshgi’s and Wes Iversen‘s photos at these links.

(credits and links in the captions)

How High Can An Eagle Fly? Can A Raven Follow Him?

Bird Behavior, Birds of Prey, Crows & Ravens, Musings & News
A raven harasses V, the new male bald eagle at Hays, 18 Oct 2023 (photo by Jim McCollum)

24 October 2023

On 18 October while Jim McCollum was taking photos of the Hays bald eagles a raven showed up and began to harass the new male eagle, nicknamed “V.”

10/18 – The new fella went for a fly about and got jumped by a Raven. The Raven chased him all over the sky. This guy needs to work on his fighting skills.

— Jim McCollum -> 40 Acres a.k.a. Hays Woods Enthusiasts
A raven harasses V, the new male bald eagle at Hays, 18 Oct 2023 (photo by Jim McCollum)
A raven harasses V, the new male bald eagle at Hays, 18 Oct 2023 (photo by Jim McCollum)

Jim’s photos were shared to the 40 Acres a.k.a. Hays Woods Enthusiasts Facebook group where Dave Dutzik remembered a story about crows that piqued my interest.

A little tidbit I read recently. Crows will lite on eagles backs and peck at their necks. The eagles don’t fight back just soar higher and higher until for lack of oxygen the crow passes out and falls off the eagles back. I’m not sure about the validity but it’s a good story!

— Comment by Dave Dutzik at 40 acres Facebook group

Is it a true story? Let’s look into it.

At what altitude does lack of oxygen affect birds?

Birds are the champions of high altitude and can breed and exercise (fly) at altitudes that kill humans. Some species are so well adapted to high altitude that they fly as high as a jet, over the Himalayas where humans die without supplemental oxygen. Even our North American songbirds fly high …

Migrating birds in the Caribbean(*) are mostly observed around 10,000 feet, although some are found half and some twice that high. Generally long-distance migrants seem to start out at about 5,000 feet and then progressively climb to around 20,000 feet.

— Stanford Birds: How fast and high can birds fly

(*) Migrating birds in the Caribbean = warblers!

Is lack of oxygen the reason why the crow leaves the eagle? No. The crow leaves because the eagle is no longer a threat or because the crow is tired.

How high can a crow, a raven and a bald eagle fly?

So the better question is: How high can a raven fly? Can a bald eagle follow him?

For more information see High-altitude champions: birds that live and migrate at altitude and this vintage article.

As High As A Jet

(photos by Jim McCollum)

Hundreds of Grackles in the Trees

Bird Behavior, Migration
Common grackle flock moving through the trees, Patuxent Research Refuge, Nov 2021 (photo from Wikimedia Commons)

18 October 2023

This month a flock of 100 to 200 common grackles has been hanging out at Frick Park, chattering in the trees and swirling in a dense flock whenever they’re disturbed. This is typical fall behavior for grackles and blackbirds but I wondered why they picked the park.

According to Birds of the World, common grackles (Quiscalus quiscula) are not very territorial during the breeding season and drop all rivalry in fall and winter. On migration and at overwintering sites they prefer to roost and feed in huge flocks, sometimes mixed with other blackbirds and some robins.

Common grackles roost near plentiful food but they don’t require wild places. Urban roosts are often favored on tree-lined streets or in parks. Their fall roosts in New Jersey can contain 3,000-500,000 birds (of which grackles comprise 33%).

This flock at Patuxent in Maryland looks to be 100% grackles.

Common grackle flock on the ground at Patuxent Research Refuge, Nov 2021 (photo from Wikimedia Commons)
Common grackle flock starting to swirl up at Patuxent Research Refuge, Nov 2021 (photo from Wikimedia Commons)
Common grackle flock mostly flown away at Patuxent Research Refuge, Nov 2021 (photo from Wikimedia Commons)

Get To Know Nature in New Jersey shows what it’s like to be in the forest with hundreds of grackles.

video by Get To Know Nature on YouTube

The huge grackle flocks probably won’t stay in southwestern PA for the winter. By December they are further south, as shown on the eBird Dec-Feb map below.

Common grackle sightings, Dec-Feb, past 10 years (retrieved from eBird on 3 Mar 2022)

But for now we have hundreds of grackles in the trees.

(credits are in the captions; click on the captions to see the originals)

They Hear the Sound of Distant Waves

Bird Behavior, Water and Shore
Wandering albatross at the Tasman Sea (photo from Wikimedia Commons)

17 October 2023

Like elephants, albatrosses can hear low frequency sounds below our range of hearing, a skill that’s very useful for their lifestyle.

Wandering albatrosses (Diomedea exulans) spend their lives making incredibly long journeys over the ocean. They are known to circumnavigate the Southern Ocean three times in one year, a distance of more than 75,000 miles (120,000 km).

Range map of wandering albatross (map from Wikimedia Commons)

To do this with the least amount of effort, they have the longest wingspan of any living bird — 8 to 12 feet (2.5 to 3.66m) — and use the wind to glide as much as possible.

The best gliding happens at updrafts over the water and the best updrafts are caused by large waves. So how do wandering albatrosses find those large waves? They hear them from very far away, possibly 1,000 miles.

According to Science Magazine, “Big waves produce a very low frequency sound, below 20 hertz, that can travel thousands of kilometers, particularly when they collide with long distance swells, such as when storms develop.”

Would an albatross approach or avoid these waves in the Southern Ocean?

video from Monthly Fails on YouTube

To figure out how the birds choose where to go, Samantha Patrick of University of Liverpool and her team tagged 89 albatrosses with GPS trackers at their breeding grounds on Crozet Island near Antarctica. When the birds returned a year later to breed again, researchers retrieved the tags and analyzed the data.

Geophysicists on the team combined the biologger recordings with infrasound monitoring data from Kerguelen Island in the Southern Ocean to build “soundscape” maps on the birds’ journeys. …

During their long-distance flights, the birds tended to change course whenever they encountered a loud infrasound, the team reports. The infrasounds often indicate wave turbulence, even storms—though it’s not yet clear how the birds make use of this information. The infrasound clearly impacted the birds’ behavior, although the scientists couldn’t identify a clear pattern of whether they avoided or aimed for these low frequencies.

— Science Magazine: ‘Voice of the sea’ may help albatrosses catch the perfect wind

We don’t know yet if they avoid or approach turbulent areas but we know they hear them. More study needed!

Turbulent sea (photo from Wikimedia Commons)

Read more in Science Magazine: ‘Voice of the sea’ may help albatrosses catch the perfect wind.

(photos from Wikimedia Commons, video from YouTube; click on the captions to see the originals)

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)