How Do Birds Fuel Up for Migration?

Today we’re hearing from Bret Serbin, the Outreach Coordinator for the Long Island Field Office, as she shares how birds prep for long-distance migrations.

As children migrate back into classrooms, their feathered friends are migrating south for the winter.

Geese are among some 350 species of North American birds that migrate long distances for the winter months. Photo by Pixabay

The arrival of fall signals the departure of many migratory birds. Every year, approximately 350 species of North American birds participate in long-distance migration. Many cover thousands of miles to reach their wintering grounds in Central and South America.

Birds as tiny as the piping plover engage in this great migration. The typical adult piping plover weighs less than 2 ounces! Yet these petite plovers travel from their breeding grounds on such Northern shores as Long Island and the Great Lakes to winter in tropical destinations like the Bahamas and Cuba.

A tiny piping plover chick that will need plenty of nutrients to prepare to fly south. Photo by Victoria Lima/ USFWS

So how do these tiny birds fuel up for their long flights?

The key to their endurance lies in wrack, the green seaweed mixture found along the high tide line on most beaches. These giant green clumps or dried plant material may seem unappealing to humans, but for many migratory shorebirds, wrack’s a snack!

 

An example of beach wrack. An abundance like this can feed lots of birds and other beach creatures!

Wrack is mostly composed of sea grass that comes loose and washes ashore with the tide. Along the way, it can collect a variety of other substances. Once ashore, this rich organic mixture becomes a habitat for a number of creatures, including plants and insects. In fact, about 40 percent of invertebrate species that live on beaches depend upon wrack.

These invertebrates serve as one of the primary food sources for birds like the piping plover. The accumulation of wrack is crucial in providing this food source since the unstable conditions of the sand and the waves make it nearly impossible for plants to grow or insects to live along the shoreline.

Those big piles may not look like much to the average beachgoer, but they provide a beachy buffet for birds en route to their winter homes.

If you’re looking to help send the birds off on a successful journey, working to maintain this important food source is a great way to start. Beach grooming and driving pose serious threats to wrack, as these activities can remove wrack from its natural place on the shore or crush this delicate ecosystem and all the organisms it hosts.

Beach raking like this deprives shorebirds of a crucial source of nutrients. Photo by Wikimedia Commons

If you live in a beach community, encourage your neighbors and beach managers to minimize beach raking in order to protect this important resource. And no matter if you’re a beach bum or a landlocked bird lover, you can help educate others about the importance of this material so that the birds can snack on wrack wherever they go.

The birds’ seasonal departure reminds us to help ensure their safe return year after year. The piping plover, for instance, has experienced such population decline as to be listed as federally endangered in the Great Lakes and threatened on the Atlantic Coast and in the Northern Great Plains.

Given its low numbers, a piping plover in flight is a very welcome sight! Photo by Steven Tucker/USFWS

With this in mind, it’s important to help the birds get fortified for their long journeys so that they can return to us in the spring.

Giving songbirds something to sing about

For birds, migration is hard. Really hard. Many migratory species travel thousands of miles through all weather conditions with limited food resources. While many mysteries still remain around bird migration, scientists are learning more and more about the whys and hows of this incredible phenomenon. And it has a group of scientists in the Northeast asking: can we make migration a little easier for some songbirds by enhancing their favored habitats?

In 2015, a collaborative project began between the U.S. Fish and Wildlife Service, the University of Massachusetts, and the U.S. Forest Service’s Northern Research Station. By collecting data on bird health and by tracking movements of migrating songbirds in the Connecticut River Valley, the team hopes to determine the best habitat types for certain migratory birds that stop over in the area.

To gather this information, the team has been capturing woodland birds during spring and fall migrations using mist nets. Once captured, birds are banded and several measurements are taken including wing and beak size. Blood is drawn from some target species and brought back to a lab for analysis. The research team is getting a picture of the birds’ overall health by determining body composition (fat, lean mass, and water content), and instantaneous refueling rates which help determine if birds are gaining or losing mass during a stopover.

Biologist measuring a songbird included in the study

Banding

least flycatcher

Bird ready for release

Preparing the nanotag

Nanotag placed on the hermit thrush

Additionally, select birds are fitted with NanoTag transmitters which allow biologists to track the birds’ movements. NanoTags are tiny tags that emit a signal that can be tracked with telemetry equipment. Biologists can identify individual birds and their locations for months using the devices that are attached to the birds with a tiny elastic harness. Among the species targeted in this study are Swainson’s thrushes, northern waterthrushes, yellow-rumped warblers, Lincoln’s sparrows, and white-throated sparrows. Data collection for this project wrapped up this spring; and over the past four years, biologists were able to band nearly 3,000 birds and fit over 200 target birds with NanoTag transmitters.

This study has been taking place within the Silvio O. Conte National Wildlife Refuge. The Refuge encompasses an impressive 36,000 acres of the Connecticut River watershed in the states of New Hampshire, Vermont, Massachusetts, and Connecticut. The team has focused its capture and banding efforts on old-field sites within the Conte Refuge for this study, including the Fort River Trail area in Hadley, MA and the Orchard Hill section of the University of Massachusetts in Amherst, MA. Each site is less than 1/3 of a mile from the Connecticut River.

U.S. Fish and Wildlife Service wildlife biologist, Troy Wilson, says, “We are interested in how physiological condition affects performance during the life stage of migration. Condition metrics – fat, lean mass, water – are used as indicators of the heath of birds, as well as a means to determine the quality of the habitats they occupy as they refuel from one location to the next.” The end goal is to determine how the Connecticut River Valley and the Silvio O. Conte National Fish and Wildlife Refuge can be a better host for migrating birds. The team hopes to be able to make recommendations for habitat management, specifically where forested areas should be converted to early successional habitat through forest management, and where old fields and shrublands might be managed for specific plant species and habitat structure that provide the highest benefits to birds during migration.

Jennifer Lynch Murphy is a wildlife biologist with C&S Engineers, specializing bird-aircraft collisions. She lives in Sunderland, MA with her husband, Kevin, and dog, Levi.

 

 

 

 

 

 

 

The American eel: Tale of a champion migrator

The American eel spawns and hatches in the ocean waters of the Sargasso Sea, near Bermuda, about 2 million square miles of warm water in the North Atlantic.

Map of Sargasso Sea in relation to NYS, USFWS

The larvae of this snake-like fish drift with the currents for about a year to find homes throughout their huge range, from Greenland to Venezuela. Many eels migrate north and make it all the way to Lake Ontario.

A champion migrator if I’ve ever seen one.

Eels go through a very complicated maturation process that usually takes them from oceanic waters to freshwater and then back to the ocean for spawning. Some eels remain in saltwater or estuaries like the Chesapeake Bay their entire lives.

If you need a reason to conserve these amazing marathon swimmers, then here are some pretty unique behaviors to keep in mind. Eels can absorb oxygen through their skin and gills, allowing them to travel over land, particularly wet grass or mud (so cool!). Eels also can cover their entire bodies with a mucous layer, making them nearly impossible to capture by hand.

Historically, eels were abundant in Lake Ontario with over 1 million documented annually migrating upstream at the Moses-Saunders Hydropower Dam on the St. Lawrence River. In 2001, there was a huge drop to 944 migrants. Numbers have increased in the last decade, but are still below 50,000, leaving biologists looking for answers.

The extreme population decline may have been fueled by the 1970s demand for yellow and silver life stages of the American eel. Harvest can be especially detrimental because of the eel’s slow and complex maturation process, but the definite cause of the decline is still not clear.

American eels no longer have access to much of their historical habitat because dams and other obstructions in rivers block their migration and prevent them from accessing all available habitat. Localized population declines are also attributed to mortality in hydropower plant turbines, degradation of current habitat, and overharvest.

Addressing these threats to the American eel and its conservation is a multifaceted approach which includes research and monitoring to increase eel access to former habitat and understand the mysterious spawning migration, as well as reducing anthropogenic mortality.

Organizations including the U.S. Fish and Wildlife Service, Canadian Department of Fisheries and Oceans, New York State Department of Conservation, the Ontario Ministry of Natural Resources and Forests, the Quebec Ministry of Forests, Wildlife, and Parks, the New York Power Authority, Hydro Quebec, and Ontario Power Generation have targeted projects to develop methods to safely pass eel around hydro dams on large rivers.

Within New York State, our field office has partnered to track eel migration in the St. Lawrence River. Eels are tagged with acoustic tags in the Bay of Quinte (on the north shore of Lake Ontario). They then travel downstream along the St. Lawrence River and can be tracked with receivers located at the Iroquois Dam, about 80 miles downriver. That migration usually takes place in late summer or early fall when the eels are maturing from their yellow form to a beautifully elegant silver mature stage.

Documented eel movements at the Iroquois Dam in NYS, USFWS

In collaboration with other natural resource agencies, the Service continues to work to mitigate adverse impacts to eels. These measures are specified during the licensing or relicensing of hydropower projects by the Federal Energy Regulatory Commision and can include the addition of facilities like eel ladders to safely pass eels upstream, screens to keep eels out of turbines, passageways to guide them downstream, or shutting turbines down at night when silver eels migrate.

Service biologists collecting eel receivers on the St. Lawrence River, USFWS

Eel ladders, which are designed specifically for this species, allow eels to swim over barriers using an ascending ramp. Eel migration is monitored at various areas both upstream and downstream to help understand and optimize eel passage inland and to the ocean.

Other conservation actions include restrictions on eel harvest by the United States and by the federal and provincial governments in Canada.

The U.S. Fish and Wildlife Service continues to work with partners to better understand and conserve this remarkable species. The more informed we can be about the species around us, the better we are able to makes conscious choices to conserve and protect wildlife and the ecosystems in which we all live.