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  • By: Nancy Pau, Wildlife Biologist

On a Wing and a Prayer: innovative technology helps to shed light on epic wildlife migrations

If someone asked me what I missed the most about my youth, I would say the freedom (and time) to pursue whatever topic piqued my interest. As a scientist, I still get to pursue inquiries and satisfy my curiosities. However, we are often limited to those topics related to our jobs. Every once in a while, an opportunity presents itself to cut across disciplines and combine our passions. Often these opportunities present themselves in the form of daunting challenges, forcing us to think outside the box, be innovative, and use every tool available to us, or even develop new tools.

Wildlife is facing some daunting challenges today, with threats such as climate change, large-scale energy development, and disease. In the face of these converging threats, conservationists are realizing that we need to know about the entire life cycle of migratory species. Whereas wildlife research has historically focused on a specific period, such as breeding, scientists are realizing that it is vital to understand the full life cycle of animals in order to design effective conservation measures. Recent research has shown that each life cycle has carry-over effects into others. A bird that doesn't breed successfully on its breeding ground or dies during migration may be led to do so because of events that happened thousands of miles away on the wintering ground and vice versa. Until recently, we have not been able to study animals that move across such long distances such as birds and bats.

In recent years, advances in technology (such as satellite GPS and geolocators) have allowed scientists to track animals across continents, advancing our understanding of their full life cycle needs and allowing us to develop comprehensive conservation strategies that address threats and vulnerabilities throughout their range. However, these technologies were expensive and heavy, allowing only limited application to larger animals. The latest innovation in wildlife tracking, nanotags, have made tracking of the smallest species feasible and affordable on a landscape and population level.

Nanotags are the very light-weight coded telemetry tags developed by Lotek, Inc. In contrast to traditional telemetry tags that broadcast on unique radio frequencies, coded tags emit thousands of unique combinations that can all broadcast on the same frequency, allowing for automated detection by computers 24/7. Dr. Phil Taylor of Acadia University saw the potential for the large-scale collaboration of a monitoring network and has helped to coordinate building and deployment of over 400 automated detection towers that cover Canada to South America. This expanding, monitoring network allows researchers to ask questions on a flyway scale, knowing that they will be able to track any tagged animals that migrate through the network.

At Parker River National Wildlife Refuge, we've been lucky to be part of the pilot Motus network since 2013. For me, being part of this multi-national, cross-discipline project has been exhilarating, challenging me to dredge up engineering and programming skills that I hadn't used since college. These early years of nanotag research have been as much about testing the technology as it has been about learning about migration and movement of our wildlife species. As we learn about the potential and limits of this new technology, our research questions and target research species have changed to take advantage of this new research tool. Even still, we have learned quite a bit more about the migratory species that use our refuge. Below, I briefly summarize what we have learned, with some conjectures, and some management implications and next steps.


Using semipalmated sandpipers as proxies, we have learned that shorebirds are longer-distance fliers than previously thought. Sandpipers have stopover durations of 2-3 weeks at the refuge, with some staying over 1 month. The majority of the tagged birds fly in an easterly or southeasterly direction when leaving Plum Island, and are not detected by towers in Cape Cod and Rhode Island. Combined with resighting and geolocator work on willets, we believe the shorebirds that leave the Great Marsh make the four-day non-stop flight over the ocean (> 2,500 miles) to land in Suriname and French Guiana, and winter in northern Brazil. From our Canadian research partners, we also know that the shorebirds that are tagged in Bay of Fundy, James Bay, and southern breeding grounds like Coats Island (top of Hudson Bay) are mainly making direct flights to South America.

The long over-ocean flight of shorebirds from breeding ground to wintering ground with only a few stopovers stresses the importance of areas that receive large shorebird concentrations during migration, such as the Great Marsh. For the Refuge, this new information highlights the importance of providing an uninterrupted resting and foraging habitat for these tiny birds while they are here. Our preliminary data shows that birds that stay longer tend to make more direct flights (over the ocean), while those that have a shorter stopover fly closer to the coast and stop at other sites. We also learned that shorebirds are relatively mobile and use a variety of habitats during their stay, from beach to salt marsh to impoundments.

Saltmarsh Sparrows

Saltmarsh sparrows are unique in that they spend their entire life in salt marshes and have their entire breeding and wintering range in the eastern U.S. They are also the poster child for sea level rise as they build their nests and raise their young in salt marshes in between monthly flooding tides. In the last decade, the Refuge has been working with partners to learn much about their breeding behavior, population dynamics, and threats such as mercury. With the expanding nanotag tower network, we finally were able to start investigating the connection between breeding, migratory, and wintering habitats in order to develop better conservation strategies for this highly imperiled species. In 2015, we deployed tags on birds in ME, MA, and RI and were able to track more than 60% of the birds as they migrated along the coast down to Virginia over a 2-month period. An animation of the sparrow's migration can be viewed here:

This fall, we deployed additional tags on saltmarsh sparrows in Maine, Massachusetts, and Rhode Island to learn more about the timing of migration and migratory routes of this sparrow during their fall migration. We also deployed tags on sparrows in South Carolina this spring to track their northward migration. Having a better understanding of where our sparrows migrate through and winter will allow us to be able to address all threats to their survival, and better understand local population trends that we see in the Great Marsh.This year, we put some tags on birds wintering in South Carolina to track their north-bound migration and deployed additional tags this fall in their breeding grounds.


Bats are quickly becoming a priority for conservation, due largely to two emergent threats that have dire consequences to their survival. White nose syndrome is an introduced fungus that is having devastating effects on our bat populations, particularly the two most abundant bats in the eastern U.S.: the little brown bat and the northern long-eared bat. Large wind energy development potentially has population-level impacts on migrating bats, particularly along mountain ridges and in coastal areas. These landscape-level questions are expensive and difficult to research, particularly for a group that has received little research funding in the past.

While we have not coordinated a large-scale study for bats as we have for the above species, we were able to work with partners to deploy a few pilot tags and learned a few things. One thing we learned was that bats may be active later in the season than previously believed. By tracking bat movement 24/7, we learned that migratory bats, like red bats, are making migratory movements later than anticipated and that local hibernating bats, like big brown bats, will emerge well into October when the weather is favorable. Working with bats has been challenging as they seem especially apt at removing the nanotags; however, the technology shows promise in being able to track red bats that migrate along the coast. This August and September, red bats and big brown bats were tagged with nanotags, and we look forward to seeing what we learn from the data.

We still have more research to do to confirm some of the hypotheses speculated above. However, this new technology has provided some surprising new data that challenge our scientific understanding of migration. The most exciting part of the nanotag project has been its demonstration that the the power of collaboration and human innovation is able to address some of the most daunting challenges we face in conservation. As a society, we're making advances in technology in leaps and bounds. I am heartened that the next generation of tech-savvy conservationists will take advantages of these technological advances in their stewardship efforts.


Nancy Pau is the wildlife biologist at Parker River National Wildlife Refuge in Newburyport, Massachusetts. Prior to coming to Parker River in 2002, she worked as a land acquisition planner for the US Fish and Wildlife Service's Northeast Region and as an endangered species biologist in Sacramento, CA. Nancy's early career taught her the importance of keeping a landscape perspective in all conservation work. Her biggest challenge at work involves figuring out how to make the refuge's coastal habitats more resilient to rapid climate change, and how to engage the local community in enhancing that resiliency. Nancy is a mother to two curious boys, ages eight and five. As a parent, Nancy is getting lots of practice developing simple explanations for complicated natural interactions and has gained an appreciation for the role of public engagement in solving many of our conservation challenges.

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