American Oystercatcher Tracking Program Evolves With GPS

The tiny backpack you see fitted on this American Oystercatcher is a solar-powered GPS/GSM transmitter. It weighs around 10 grams (less than 3% of this bird’s total body weight) and is fitted to the bird using a leg-loop harness, applied by a trained biologist.

The small solar panel recharges the battery, enabling the transmitter to operate for years without maintenance. It records GPS coordinates at a set time interval and transmits it via a GSM (cellular) network to our research database, providing daily data.

In partnership with Wildlife Biologist Min Huang of the Connecticut Department of Energy and Environmental Protection, we fit five oystercatchers with transmitters this 2025 breeding season.

The fantastic five didn’t know it, but they were our pilot group of birds!

EXPANDING BEYOND BANDING

For years, Audubon staff in Connecticut has been fitting birds with field-readable leg bands, each with a unique alpha numeric code. This enables researchers and the public to re-sight individual birds with binoculars or a spotting scope. Including this season when we banded 13 new birds, we have banded a total of 63 adult birds, composing 28% of Connecticut's breeding population, in addition to 30 fledglings.

The re-sights are submitted to the American Oystercatcher Working Group band database. We’ve learned that our Connecticut breeding birds are overwintering across a large range from New York down to the west Coast of Florida.

The GPS/GSM transmitters are an important advancement of this program. With regular, detailed mapping of oystercatcher migration routes and stopover sites, we aim to identify important fall and winter habitats for oystercatchers and work with partners across the hemisphere to co-develop conservation plans.

FIVE BIRDS, DOZENS OF DIFFERENT ROUTES

The five GPS/GSM transmitters were deployed at the mouth of four major rivers in Connecticut. Two were deployed on a breeding pair at Long Beach in Stratford, one on a breeding female at Sandy Point in West Haven, one on a recaptured male at Griswold Point in Old Lyme, and the remaining transmitter on a breeding female at Bluff Point in Groton.

At Long Beach, the female (fitted with yellow leg band N92) and male (fitted with yellow leg band N93) had sadly suffered a nest loss just before transmitter deployment. Both adjusted well to the new tracking devices - however they split up soon after.

The female (N92) left Long Beach and traveled 12 miles to Cockenoe Island in Westport, regularly visiting nearby Goose Island in Norwalk, then back to Cockenoe. There, she was observed with a new mate but unfortunately did not successfully nest again.

In mid-August, N92 flew back to the Stratford and Milford Point area to join the staging flock of oystercatchers. On September 30, she began her fall migration, stopping in Cape Lookout, North Carolina before continuing to her final wintering location - bouncing back and forth across the border of Georgia and South Carolina.

Her original partner, N93, did not remate. He returned to the same staging area, joined the same group, and began his migration on September 30, also stopping at Cape Lookout, North Carolina before settling for the winter at Horseshoe Beach off the west coast of Florida.

The other three birds fitted with transmitters have so far been tracked to Virginia, the west coast of Florida, and the marshes of New Jersey just north of Atlantic City. Quite a spread!

NEXT STEPS FOR THE TRACKING PROJECT

We have learned so much about our five Connecticut breeding American Oystercatchers to-date and collected an incredible amount of data.

Our colleagues from Manomet in Virginia have already captured photos and video of N92, and folks surveying the west coast of Florida have also gotten a photo of N93.

Going forward, we hope to expand the project, start data analysis, and work with partners to identify conservation priorities that will shape future management efforts.

Here in Connecticut, we will be able to learn more about the birds utilizing our offshore islands to nest, and we can better study feeding behavior – from the places birds forage, to the distances they fly to find food – and how it all impacts their chicks’ survival.

*All banding, marking, and sampling is being conducted under a federally authorized Bird Banding Permit issued by the U.S. Geological Survey’s Bird Banding Lab.