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.
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).
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.”
As fall migration continues, raptors swell the southbound stream. At the Allegheny Front Hawk Watch (closest to Pittsburgh), broad-winged hawks peak in September, sharp-shinned hawks in October, red-tails in late October, and golden eagles in November. Peregrines are rarely seen, averaging just 34 individuals per season. Their numbers peak in the first week of October.
Peregrines are rare at the Allegheny Front Hawk Watch because they are not numerous to begin with and the watch is far from their typical migration routes. However, many peregrines are never counted on migration because they don’t migrate at all. It depends on where they breed.
Arctic peregrines are truly migratory. Their food sources — nesting shorebirds, seabirds, and songbirds — leave the arctic from July through September so the peregrines must leave, too. A decade ago The Southern Cross Peregrine Project (SCPP) satellite tracked a dozen arctic peregrines wintering in Chile and found that those that breed in northeastern Canada always leave around the September equinox.
From there, unless major weather diverts them, northeastern arctic peregrines typically fly due south to join the Atlantic Flyway. In the spring they track west and follow the Central Flyway. The map below shows five years of satellite tracking of an arctic peregrine, “Island Girl,” on her migration south from Canada to Chile (red) and returning in the spring (blue).
Meanwhile adult peregrines in eastern North America generally don’t migrate at all. Urban peregrines remain on territory year round because their food supply is constant (pigeons) and actually increases in the fall when migratory songbirds arrive for the winter. Adult peregrines may move a short distance during winter scarcity but not necessarily south. Juveniles definitely wander.
The animated PA Game Commission map below shows nine months of wandering by a juvenile peregrine that hatched at the Gulf Tower in Spring 2002. The bird left Pittsburgh on 1 July and wandered to New Jersey, the Chesapeake, Virginia, Maryland and Pennsylvania. This was only the beginning.
Juvenile peregrines wander until they reach maturity at age two, then wander to find a breeding territory. Good nesting “cliffs” are scarce so these floaters may wander for years. When they finally claim a nesting site they won’t leave home unless an even better site becomes available.
Do Pittsburgh’s peregrines migrate? No. I see them in person and on the National Aviary nestcam from November through February when migratory peregrines are in South America.
(photos from Wikimedia Commons; click on the captions to see the originals. Telemetry map of juvenile peregrine falcon banded at the Gulf Tower in Spring 2002 (animation from PA Game Commission, 2003). This animation is no longer available on the PGC website)
Nowadays women falconers work at raptor centers, aviaries and bird abatement services that use falcons and hawks to move nuisance birds.
At top, a woman falconer works with a gyrfalcon at the Salzburg Regional Falconry Centre at Hohenwerfen Castle, Austria where they hold daily flight demonstrations with various birds of prey. The falconers live at the castle so they can better take care of the birds.
Have you seen an unusual white squiggle on a green leaf? The pattern was made by a leaf miner, a tiny insect larva that eats a path between the top and bottom surfaces of the leaf. The path ends when the larva is ready to pupate. When the insect departs it leaves a hole.
There are many tiny moths, beetles, sawflies and flies that make leaf mines. Some create blotches. Others, like this one, make serpentine paths. You can identify the insect(s) that made the paths — or at least narrow the number of species — by noting the type of mine and identifying the plant host.
The larvae of a tiny fly, Liriomyza eupatoriella. (NOTE: While researching this insect I discovered Charley Eiseman, an expert on leafminers and author of the only photo of the bug at bugguide.net. More on Charley Eiseman below.)
As the egg-shaped fruiting body matures it ruptures and the spongy spore-bearing stalk emerges; fully grown, it may be from 0.4 to 5.9 inches long and 0.6 to 0.8 inches thick. The stalk is hollow and strongly wrinkled overall; its shape is cylindrical below, but it gradually tapers to a narrow apex with a small opening at the tip.
The one we found was an old specimen. When new, the stalk stands up and the upper third is coated with a stinky greenish-brown spore-containing slime that attracts flies to bear away the spores. Here’s a newer specimen, photographed in Florida.
There are even more suggestive specimens here and here.
The devil’s what?!
p.s. At least one of the ladies in our group is not retired but she is a grandmother so I invoked my poetic license to describe us.
(top photo by Kate St. John, second photo from Wikimedia Commons; click on the caption to see the original)
The remnants of Hurricane Ida held back bird migration for two days in Pittsburgh but the logjam has broken. Today and tomorrow hold the promise of many migrating birds in southwestern Pennsylvania including mixed flocks of confusing fall warblers. Here’s a tip on how to identify them. This even works hours later at home with your reference guides.
In the field with a hard-to-identify bird, write down every feature you see as if you were going to draw the bird. Don’t forget habitat and behavior.
Details, details, details! The more details the better. If you get only a fleeting glimpse describe whatever jumps out at you.
The details will be useful when you get home and look at field guides.
Let’s try it on this bird.
At first glance (squint your eyes to see less):
perched in a tree
smaller than a sparrow; warbler size
charcoal gray back
white wing bars
(Under the Tail is important too but we can’t see it here.)
Coquina clams (Donax variabilis) are tiny saltwater molluscs found on sandy beaches from Virginia to Texas. Their variable colors are beautiful and at only 3/4 inch long they are just the right size for collecting. I usually find an empty half shell rather than two joined like butterfly wings (above).
Since I only pay attention to empty shells I never thought about where they live and how they get there until I saw this video. Watch two coquina clams disappear in the sand.
I find it very peaceful to watch coquina clams slipping into the sand where the ocean meets the land. Video from July 2021 near St. Augustine, Florida. pic.twitter.com/wWtp6rhxvE