Turning tragedy to treasure: Preserving dead birds teaches us about live ones

When a songbird is plucked out of the air by a speeding Peregrine Falcon, we celebrate its role in the food chain. But millions of birds die less heroically as a result of cars, house cats, or plate-glass windows. Whenever possible, we try to salvage those casualties and put them to good use. If their skins and tissues are preserved in a natural history collection, scientists can use them to study changes in populations over time and space. One recent study of specimens showed that several Australian bird species have evolved smaller body sizes over the past century (Gardner et al. 2009). Systematic salvage efforts will help us to discover whether the same phenomenon may be happening in North American birds.

The Museum of Southwestern Biology (MSB) of the University of New Mexico has been opportunistically salvaging dead birds for over 25 years, and those efforts are beginning to pay scientific dividends. In one study, we used road-killed Short-eared Owls to show that females winter farther south and migrate later in spring than males (Dickerman & Witt 2012). In another study, we used hunter-killed Sandhill Cranes to show how their exceptionally long windpipes evolved (Jones & Witt 2014) and how they can be used to distinguish subspecies based on subtle acoustic differences (Jones & Witt 2012).

Bob Dickerman skinning a salvaged Marabou Stork
Bob Dickerman skinning a salvaged Marabou Stork

One of the most exciting emerging areas in ornithology is the study of migratory connectivity among populations. In 2015, we still don’t know with precision where most birds that winter in New Mexico breed, nor do we know where most birds that breed in New Mexico spend the winter. Current studies by MSB students and staff are studying these questions in the Hermit Thrush and the Yellow-rumped Warbler, two commonly salvaged species for which migratory connectivity is poorly known. Ultimately, genomic and stable isotope analyses of museum specimens will allow us to establish these connections for every species, providing critical information for conservation.

Donna Schmitt skinning a salvaged Tufted Puffin (her 9000th specimen prepared).
Donna Schmitt skinning a salvaged Tufted Puffin (her 9000th specimen prepared).

The most abundant species are also the most commonly salvaged. Although we can’t save every Mourning Dove and House Finch carcass for posterity, we try to save enough to allow future scientists to study change over time. Surprisingly often, salvaged carcasses produce exciting discoveries. Recently, salvaged birds arriving at the MSB have included the state’s first Sooty Tern (Johnson et al. 2011), Long-billed Murrelet (Witt et al. 2010), and “Dusky” Great-horned Owl (Dickerman et al. 2013), respectively. In a recent study, we serendipitously discovered that a specimen salvaged in Chicago and assumed to be Yellow-bellied Flycatcher was in fact the first Illinois record of a Western Flycatcher (Baumann et al. 2014). That bird had been salvaged by a volunteer citizen-science project focused on migrating birds that collide with buildings in Chicago (Chicago Bird Collision Monitors of the Chicago Audubon Society).

Andy Johnson prepares a Trumpeter Swan that was salvaged at Bosque del Apache NWR
Andy Johnson prepares a Trumpeter Swan that was salvaged at Bosque del Apache NWR

Salvaging dead birds is tricky due to the strict laws that protect bird populations. Federal and state laws prohibit possession of wild birds without permits. Current law doesn’t allow for citizen-salvage, but an important workaround is that educational and scientific institutions are allowed to obtain and possess wild birds, even if they don’t have permits1. At the MSB, we maintain state and federal permits for salvage of wild birds, and we also work with other institutions that can legally salvage and transfer birds to us. By coordinating with institutions to safely and legally conduct salvage, citizens can help to prevent dead birds from going to waste. MSB has many institutional partners that provide salvaged birds. Among our partners, Wildlife Rescue, Inc. (Albuquerque), The Wildlife Center (Española), and Desert Willow Rehabilitation Center (Carlsbad) have provided a tremendous number. These and other wildlife rehabilitators in New Mexico work hard to care for sick and injured wildlife and to make the most out of birds that can’t be saved.

Dead birds can be biological hazards. There are bacteria, viruses, and fungi that can be carried by wild birds and are capable of making humans sick. Avian influenza is a well known example, although the highy pathogenic strains that have infected humans are not yet known from the New World (but see this December 2014 discovery from WA!). West Nile Virus is commonly found in New Mexico birds, though transmission occurs via mosquito. The risk of getting sick from a bird carcass is small but definite, so dead birds should always be treated with caution.

When salvage can be accomplished safely and legally, we use an inverted plastic bag to pick up the carcass. We write a note with the exact location, date, finder’s name and contact information, and the context or suspected cause of death (e.g. “found dead below window”). We seal the bird with the note in plastic (ideally double ziplock-bags with the air squeezed out) and freeze it. As soon as possible, we transfer the specimen to a non-frost-free chest freezer at the MSB. At that point, the Collections Manager and student assistants will assess the identity and condition of the bird. The more valuable the bird is for research, the more parts we will attempt to preserve and archive. Eventually, all of the bird’s information will go to our online database, where it will be accessible to everyone. Learn more about the MSB and read what we have been publishing at our website.

References and footnotes

Baumann, M. J., N. D. Pederson, S. C. Galen, & C. C. Witt. 2014. Simple technique for distinguishing Yellow-bellied Flycatchers from Cordilleran and Pacific-slope flycatchers. Journal of Field Ornithology 85:391-396.

Dickerman, R. W., S. M. McNew, & C. C. Witt. 2013. Long-distance movement in the “Dusky” Great Horned Owl and current limits to phylogeography for establishing provenance. Western North American Naturalist 73(4):401-408.

Gardner, J. L., R. Heinsohn, L. Joseph. 2009. Shifting latitudinal clines in avian body size correlate with global warming in Australian passerines. Proceedings of the Royal Society of London B 276:3845-3852.

Johnson, A. B., S. M. McNew, M. S. Graus, and C. C. Witt. 2011. Mitochondrial DNA and meteorological data suggest a Caribbean origin for New Mexico’s first Sooty Tern (Onychoprion fuscatus). Western Birds, 42:233-242.

Jones, M. R., and C. C. Witt. 2012. Vocal formant spacing reveals subspecies composition of non-breeding Sandhill Crane populations. Wildlife Society Bulletin36:47–53.

Jones, M. R., & C. C. Witt. 2014. Migrate small, sound big: Functional constraints on body size promote tracheal elongation in cranes. Journal of Evolutionary Biology 27:1256–1264.

Witt, C. C., M. S. Graus, and H. A. Walker. 2010. Molecular data confirm the first record of Long-billed Murrelet (Brachyramphus perdix) for New Mexico. Western Birds, 41:160-167.

Witt, C. C., and R. W. Dickerman. 2012. Differential migration by sex in North American Short-eared Owls (Asio flammeus). Western Birds, 43:36-47.

1 From 50 CFR § 21.12: “State game departments, municipal game farms or parks, and public museums, public zoological parks, accredited institutional members of the American Association of Zoological Parks and Aquariums (AAZPA) and public scientific or educational institutions may acquire by gift or purchase, possess, transport, and by gift or sale dispose of lawfully acquired migratory birds or their progeny, parts, nests, or eggs without a permit…[provided that certain conditions are met].”

Adapted from a similar article that I wrote for Bosque Tracks Newsletter — special thanks to Jean Mason.

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