Banding Songbirds in Assateague Island's Maritime Forest

By Emma Cummings, Scientists in Parks intern, Assateague Island National Seashore. Park contact: Tami Pearl, biological science technician.

The MAPS programme

The Institute for Bird Populations created Monitoring Avian Productivity and Survivorship (MAPS) to study why bird populations are declining, how climate change affects them, and where conservation is most needed. The first stations opened in 1989; by 2024 there were more than 1,200 across the United States and Canada.

Assateague Island National Seashore opened a MAPS station in 2022 to learn about the health of its maritime forest birds — in particular how well songbirds breed in the island's loblolly pine forest. Barrier-island maritime forests are unique habitat, threatened by sea-level rise and destructive insects.

Technicians processing a bird at the banding station. NPS.

A day at the station

• The day starts hours before dawn. As the sun rises through the pines, the team opens ten mist nets spread evenly through a 20-acre stand.
• Forty minutes later comes the first net run: each net is checked and any birds caught are gently removed.
• At the station, each bird is weighed and fitted with a small numbered metal leg band, so it can be recognised whenever it is caught again — showing when and where it was first banded.
• Measurements and plumage details reveal its age and sex. Then it is released unharmed.
• After six hours, the nets are closed. The team returns about 10 days later.

White-eyed vireo. NPS.

Three years of banding

535 birds of 39 species were banded over the first three years.

In 2023, gray catbirds were the most abundant. NPS.

Notable moments

• In 2023 the team caught a record 24 warblers of 7 species.
• A house wren banded on August 2, 2022, as an adult male has been recaught every year — at a different net each time, but always in the forest's southwest corner. By 2024 he was at least 3 years old.

Plumage of a second-year eastern wood-pewee. NPS.

Birds as a measure of forest health

The NPS Northeast Coastal and Barrier Network monitors forest health on Assateague — structure, composition and wildlife — on long-term plots in the maritime forest, surveyed since 2019. Because bird diversity and population trends are indicators of forest health, park managers added the MAPS station. Forest-dependent species such as the pine warbler and eastern wood-pewee breed here and need a healthy forest year after year, so the two data sets together track the forest over time.

Did you know? Banders also score how much fat a bird carries — it shows yellowish just under the skin. Birds overeat (hyperphagia) about two weeks before migrating, so plenty of fat can mean a bird will leave soon.

Sources

• National Park Service, Assateague Island National Seashore, "Monitoring Avian Productivity and Survivorship at Assateague Island," by Emma Cummings. https://www.nps.gov/articles/000/monitoring-avian-productivity-and-survivorship-at-assateague-island.htm
• The Institute for Bird Populations, MAPS: https://www.birdpop.org/pages/maps.php · NPS Inventory and Monitoring at Assateague Island: https://www.nps.gov/im/ncbn/asis.htm
• The original cites Drever and Martin (2010), Segura and others (2014) and Guillemette and others (2012) on birds as indicators and on migration fattening.
• Words on this page from people and organisations outside the federal government are paraphrased; rewritten in hubnx's own words.