Guest Post: Who Puked? Raptor Pellets and eDNA

This post was contributed by Allison Walker, Mika Kirkhus, Rielle Hoeg, and Dave Shutler, authors of a recent paper in The Wilson Journal of Ornithology about using eDNA to identify raptor pellets.

Mika holding a raptor pellet found on a fieldtrip in Norway. Photo by Mika Kirkhus.

In the field, bird researchers regularly encounter raptor pellets, which are regurgitated clumps of indigestible animal material such as fur, feather, and bones. However, where multiple species of similar-sized raptors occur, it can be hard to tell which species produced a pellet based on the pellet’s appearance alone. After field seasons spent on two Nova Scotian islands collecting raptor pellets as part of a study on predation on seabirds, one sample of pellets raised our eyebrows. The pellets we collected from an island known to host Great Horned Owls were small, about half the size of a computer mouse; those we collected from another island were huge ⁠— easily four times the size. We speculated about what could have disgorged such a monstrosity. Could it have been a Snowy Owl? Probably not, given the similar size of the two owls. An eagle? Seemed more likely, but how could we know for sure? Thus, we became interested in developing a way to identify bird species producing pellets based on residual environmental DNA (eDNA). We suspected DNA in pellets could come from a bird’s digestive tract cells, leaving behind a genetic signature in the field telling us “Who puked?”

Continue reading

Guest Post: Egg Cannibalism in Gulls

This post was contributed by James L. Hayward, corresponding author of a recent paper in The Wilson Journal of Ornithology describing the occurrence and impact of egg cannibalism on a Glaucous-winged Gull colony.

An egg cannibal eating the contents of a stolen egg. Photo by James Hayward.

Over the course of many field seasons at a colony of several thousand Glaucous-winged Gulls at Protection Island National Wildlife Refuge, Washington, I noticed large accumulations of broken eggshell littering a few of the nesting territories. I watched the owners of these territories invade the territories of fellow residents, grab an egg, fly the egg back to their own territories, and eat the contents. Eggshell fragments from the stolen eggs accumulated on the territories of these egg cannibals.

Continue reading

Guest Post: An Air Compressor System for Bird Banding

This post was contributed by WOS member Annie Lindsay, lead author of a recent paper in North American Bird Bander about the air compressor system she describes here.

Annie Lindsay uses the air compressor system to examine a bird. Photo credit: Powdermill Nature Reserve / Carnegie Museum of Natural History.

Bird banders take standard measurements on all birds they process as they build their datasets, some of which require banders to use their breath to blow gently to part a bird’s feathers. One of the most universal of these measurements is an inspection of the fat layer visible under the skin, which gives information about things like migratory readiness and refueling performance. Depending on the season, banders may also need to part feathers to check for breeding condition (whether the bird has a brood patch or cloacal protuberance), the level of skull development (which aids in ageing), and any sign of molt activity.

Continue reading

Guest Post: Radio-Tracking Eastern Towhees in Central Kentucky

This post was contributed by Megan Martin, lead author of a paper in a recent issue of the The Wilson Journal of Ornithology documenting her findings on the ecology and behavior of towhees in the nonbreeding season.

Student researcher Megan Martin smiles with a captured Eastern Towhee in 2015. Photo by Dr. David Brown.

As a member of the Honors Program at Eastern Kentucky University, I was expected to write an undergraduate thesis. Since my major was wildlife management and I had just completed an incredible internship with the National Audubon Society, I knew I wanted to study birds. With the help of Dr. David Brown, I began to research a quirky shrubland bird known as the Eastern Towhee. We are only beginning to understand the non-breeding season ecology of shrubland bird species. The amount and quality of food that an individual bird is able to find in the non-breeding season seems to have lasting effects through other seasons of the year, potentially affecting its arrival time on its breeding grounds, health, survival, and breeding success. Therefore, winter habitat quality may have population-level impacts. We hope that learning more about the winter behavior of these birds will give us a greater understanding of what factors have led to population changes, especially since towhees and other shrubland bird species are in decline.

Continue reading

Guest Post: A Starling Helps Raise Woodpecker Babies

This post was contributed by Dominic Janus, lead author of a paper in a recent issue of the The Wilson Journal of Ornithology documenting a European Starling feeding nestlings at a Hairy Woodpecker nest.

A starling about to deliver food to a woodpecker nestling.

European Starlings are an invasive species in North America. They’re known to harass native woodpeckers and take over active woodpecker nests for their own use. So imagine my surprise when I happened to find a Hairy Woodpecker nest with three young in spring of 2020 being fed by a mother woodpecker and a starling! For the mother woodpecker, this was as if a known intruder entered her home, helped feed her family and clean her house until her kids were grown, then disappeared. This bizarre behavioral narrative is not complete without the events that led me to discover it, so I’ll begin there.

Continue reading