On August 7, we completed our second season running a MAPS station in the northwestern section of Manual F. Correllus State Forest (MCSF). In the course of seven days of mist-netting throughout the breeding season, we captured 130 birds of 18 species, including 20 hatch-year birds that were produced in the vicinity of the MAPS station.
Our station is one link in this long-term monitoring project that focuses on Monitoring for Avian Productivity and Survivorship (MAPS). Across the continent, about 1,200 stations like ours gather data on which species are nesting and producing fledglings (productivity), and which individual birds return in the years following their initial capture (survivorship).
We operate 10 mist nets to capture breeding birds in three habitat types that are characteristic of MCSF: oak forest, a fire break with a mix of grasses, shrubs, and a few trees, and a scrub oak thicket. Each of these habitats supports a distinctive mix of breeding birds, so our station monitors a broad selection of the birds that nest in Correllus.
Luanne Johnson checking a net in the oak forest habitat.
Rich Couse sets a net in the open fire break habitat.
Samantha Bryn extracts a bird from a net in the scrub oak habitat.
Because MAPS is all about breeding birds, we document all of the birds we can find within the MAPS station area. This adds up to about eight hectares and includes the area around our array of 10 mist nets plus a 100 meter buffer. We note birds we see or hear singing as well as those we capture.
We documented 37 species of birds at our station this season, but only 18 of those species were represented in our mist net captures. We don't expect to capture large, high-flying species such as osprey, turkey vulture, or red-tailed hawk. But this season, there were two locallly breeding songbird species that seemed to mock us as they sang near our nets. These "nemesis birds" were red-eyed vireo and eastern kingbird. Two species captured for the first time this year were field sparrow and pine warbler. On our wish list were the yellow and black-billed cuckoos that called regularly around our station.
With so much shrub habitat in our station, it was not suprising that the most frequently captured species were the thicket-loving eastern towhee (24 captures) and common yellowthroat (21 captures). Other numerous shrub-nesting species were prairie warblers (16 captures) and gray catbirds (13 captures). Our 18 black-capped chickadee captures included a couple of family groups with multiple hatch-year birds in each group.
We captured 20 hatch-year birds representing eight species this season: black-capped chickadee (8), eastern towhee (3), eastern bluebird (3), ovenbird (2), gray catbird (1), tufted titmouse (1), common yellowthroat (1), and field sparrow (1). Some recently fledged birds look quite different from their adult parents. Two examples found at our MAPS station are eastern towhee and eastern bluebird. I have included some images for you of an adult of each species as well as a hatch-year individual not long out of the nest. Those young birds will molt their body feathers and some wing coverts, which will change their appearance again.
A male eastern towhee.
A hatch-year eastern towhee.
A male eastern bluebird.
A hatch-year eastern bluebird.
All birds in the images here were captured, handled and banded with both federal and state permits for bird research.
A great-crested flycatcher recapture from 2025.
Tracking birds that survive from one year to the next is another important part of MAPS data collection. Our second season allowed us to begin tracking survivorship at our MAPS station. We recaptured eight of the 68 birds we banded in our first season (2025). Two of those birds were black-capped chickadees we banded as hatch-year birds (a male and a female).
Fledging from a nest and becoming a hatch-year bird is the first major achievement in a bird's life. Its next feat is to survive its first year. For species that do not migrate, like black-capped chickadee, this requires learning how to survive in harsh winter conditions and how to avoid predators like sharp-shinned hawks and eastern screech-owls. So we were very happy to recapture these two birds in their second year. Our other recaptures had already been adults last year, so we do not know their ages. These included eastern towhees (two males, one female), a male common yellowthroat, a male Baltimore oriole, and a great crested flycatcher. We don't know where the towhees spent the winter, since the species is partially migratory but present year-round on Martha's Vineyard. We do, though, know that the other birds all made lengthy migrations to their wintering grounds and then returned to Correllus for the breeding season. We hope to see them again next year.
One of the oddest things you will witness at a bird banding station is a bird bander blowing on a bird in her hand. We aren't trying to "turn them on," nor are we trying to cool them off. Instead, this peculiar human behavior, shared by a variety of "-ologists," is a gentle way separate feathers or fur for a look at the skin and tissues underneath. This helps determine the animal's breeding status and, in birds, the molt (feather replacement) status as well.
Specifically, we are looking for a brood patch (BP) on the lower belly of a bird and/or a cloacal protruberance (CP) on a male bird. A BP is a patch on a bird's belly that drops its feathers and becomes vascularized, allowing increased heat transfer to eggs during incubation. A CP forms when the area around a male bird's cloaca swells with sperm. Both of these are scored based on how developed they are on the bird. If you happen to be around when a bird receives a CP score of 3, you might hear an "Oh my!" or "Impressive!" from another bander. A fully developed CP is quite something to see on a small bird.
Liz Olson and Luanne Johnson checking for a brood patch on a gray catbird.
Samantha Bryn checking for a brood patch.
After we assess the breeding status of a bird we've netted, we make notes on any feather tracts molting at the time of capture. Birds don't want to expend energy growing feathers during the nesting season, which already demands enormous energy. So many species wait to molt until they are finished or nearly finished with the breeding season.
Many of the birds we capture are molting by late July or early August. Brood patches on females are filling in with new pin feathers. Most of the adult birds we capture have begun molting in a new set of flight feathers in their wings and tail. They may be missing a few feathers on each wing and sometimes have only one or two tail feathers intact during this molt. We note which feathers are molting and the extent of the bird's body molt, as well as the shape and color of the feathers that have not molted. All of these pieces of information help us assign each bird age, molt, and plumage codes within what's known as the Wolf-Ryder-Pyle system. After getting a measurement of its wing chord, we place the bird in a small section of pvc pipe on a scale to measure its mass, and then we release it.
A baltimore oriole with her brood patch re-feathering post-breeding.
This baltimore oriole is almost finished growing new primary feathers and is starting to molt its secondary feathers.
A baltimore oriole flies free after processing.
With our second season behind us, we have been busy proofing our data and completing multiple MAPS data forms as we prepare to submit our data to the Institute for Bird Populations, which leads the MAPS program. We will also upload our data to the U.S.G.S. Bird Banding Lab and report it to Mass Wildlife. We are already looking forward to the 2027 MAPS season, when we hope to see some of our feathered friends again.
We are grateful to the Martha's Vineyard Community Foundation for a 2024 grant that funded the equipment for our MAPS station, and to our donors who fund staff time to run the station. We are also grateful to the Massachusetts Department of Conservation and Recreation, which owns and manages Correllus State Forest, for their cooperation and partnership.
