Monitoring Project to Track Migrating Birds

Pennsylvania Game Commission

American woodcock will be monitored, young forest dwellers that share habitats with New England cottontails, ruffed grouse, blue-winged and golden-winged warblers, and more

HARRISBURG – The U.S. Fish and Wildlife Service has agreed to support a proposal to further expand the Motus Wildlife Tracking System in Pennsylvania and four other states to monitor eight migratory species of greatest conservation need and other wildlife.

The Pennsylvania Game Commission will lead a team involving the Maryland Department of Natural Resources, Northeast Motus Collaboration and other partnering organizations to collect life-cycle information on seven migratory birds and one bat whose populations have been in serious declines for years, and in some cases, decades.

American woodcock removed from mist net

Wildlife biologist removes American woodcock from mist net. Researchers capture woodcock, outfit them with tracking devices, then monitor them to learn about their migratory routes and habitat choices./G. Krausse

The Northeast Motus Collaboration is a partnership of the Willistown Conservation Trust, Ned Smith Center for Nature and Art, Project Owlnet and the Carnegie Museum of Natural History’s Powdermill Nature Reserve. The collaboration is housed under the Motus Wildlife Tracking System, established in 2013 by Bird Studies Canada. The network currently tracks wildlife from more than 500 stations around the world.

The USFWS is providing $497,929 to help underwrite this wildlife surveillance, which tracks migrating animals through the use of nanotags – radio transmitters so small they can be fitted to monarch butterflies. Collaboration member organizations and others are providing more than $225,000 to meet federal matching funding requirements.

The Pennsylvania species targeted by this fieldwork are Swainson’s thrush, wood thrush, blackpoll warbler, Canada warbler, rusty blackbird, American woodcock and northern long-eared bat. Other priority species, such as New England’s Bicknell’s thrush, also are targeted by this research.

“This project embodies contemporary wildlife conservation: state and federal government agencies working with private conservation organizations and universities to help species that demand more attention than traditional wildlife management can provide,” explained Game Commission Executive Director Bryan Burhans. “The agency is indebted to partner organizations, such as the Willistown Conservation Trust and the Ned Smith Center for Nature and Art, for their commitment to wildlife. Today, conservation counts on partners more than ever before.”

Nanotags are the innovation that makes this research possible. They weigh as little as one-eighth the weight of a penny and can accomplish what much heavier telemetry gear couldn’t do as recently as 10 years ago. Almost overnight they have helped strengthen the science used in wildlife conservation.

Nanotags transmit a signal that can reach out about 10 miles. This project aims to provide more receiver stations to collect those nanotag transmissions. Currently, there are more than 40 in Pennsylvania. The expectation is that about 12 more receiving stations would be added under this proposal.

“Pennsylvania already is well equipped with receiving stations in western and southern counties,” explained Dan Brauning, who supervises the Game Commission’s Wildlife Diversity Division. “Clusters of new receiver stations will be established on the Pocono Plateau, as well as across the northern tier, and along the Kittatinny Ridge/South Mountain system.”

But this proposal covers more than Pennsylvania. It will work to establish more receiving stations in four other states: New York, Maryland, New Jersey and Delaware.

Receiver stations already are collecting information that has been studied by ornithologists and bat biologists. Soon, these scientists will know more about the specifics of migration than ever before.

“Riding on the back of a migrating bird is the best way to collect migration information,” Brauning noted. “And now nanotag transmitters can do that. It’s like a new chapter in migratory bird behavior opening before us, and we all are eager to see what those transmitters continue to detect.”

Other objectives of the telemetry surveillance project include:

  • Northern long-eared bats will be tagged at a Centre County maternity colony and tracked to establish their migratory routes and use of hibernacula during the summer and winter of 2019.
  • American woodcock and wood thrushes captured at banding stations and rescued from window collisions will be tagged and their movements and survival tracked.
  • Swainson’s thrushes will be tagged to measure their migratory movements and use of hemlock habitat in Forest and Warren counties with an aim to protect critical thrush habitat.


Overall, the project should deliver more information on bird migration routes, timing, and post-breeding dispersal movements. It also has the potential to provide life-cycle data that would help protect currently unrecognized important habitat, such as high-use migratory stop-overs.

“This work has the potential to increase our knowledge of one of North America’s most important inland migratory corridors,” Brauning explained. “Little is really known about migratory stopover and staging of birds. Migration also is believed to cause an estimated 85 percent of annual adult bird mortality.”