The Fruits of Our Labors

By: Bird Program Staff

It’s hard to believe that fifteen years have passed since we first began studying the birds of Rushton Woods Preserve. Only a few years prior, Rushton Farm had been established by Fred de Long as one of the region’s first regenerative farms within a nature preserve owned by a land trust. At that time, most of the Willistown Conservation Trust’s board members were opposed to adding the farm to the heart of this 86-acre nature preserve. They believed farming occurs at the expense of wildlife; however, they soon discovered Fred was an organic farmer committed to proving that agriculture can serve as the baseline for wildlife conservation. Today Rushton Farm is not only the heart of the organization but also a nationwide model of regenerative agriculture on conserved land.

The bird banding data we have collected over the years has allowed us to demonstrate the mutually beneficial relationship between regenerative farming and the surrounding ecosystem. We have now banded 20,830 individual birds of 104 species since 2010. These include songbirds using Rushton as a stopover habitat during migration, as breeding territory, as a year-round residence, or as wintering grounds.

With so many years of data gathered, we can now begin focusing on trends. We notice that spring and fall migrations look as if these bird populations are in decline, but our breeding bird populations (studied within the national MAPS program: Monitoring Avian Productivity and Survivorship) are increasing. This year, we focused on our birds returning with bands from previous years, a parameter that—while often overlooked—is becoming more prevalent in our long-term dataset.

Spring 2024

Spring started cold and quiet, with the bulk of our capture finally occurring in May. Capture rates remained similar to last spring, but overall they were the two lowest capture rates in station history. Diversity was also similarly low to the previous spring of 33 species. The species that continue to show significant declines are the Gray Catbirds and warbler species. We did capture our 20,000th bird this spring, which happened to be a Gray Catbird—still our most common species despite the declines.

The decline in warblers is mainly in the number of individuals rather than the diversity. For example, in 2022, we had the highest diversity of species, but the third lowest capture rate for warblers. The succession of our hedgerow habitat (i.e., trees growing taller and replacing shrubs) could contribute to catching fewer individuals as the canopy is getting higher; the canopy is where many warblers love to forage!

Focusing on the birds returning between years, the outlook is brighter. About 26% of all birds captured during spring migration 2024 were returning from previous years! In April alone, two White-throated Sparrows were our own recaptures — one from spring of 2022 and another from spring of 2023 — indicating that these individuals loyally return to Rushton each winter or use it as a reliable refueling site on their northbound journeys.

In terms of returning breeding birds, 16% of the Gray Catbirds and 36% of Common Yellowthroats sported bands from previous years. One of the catbirds was a recapture from 2018, making it about seven years old. Meanwhile, of the three Baltimore Orioles we caught, two already had their bracelets! Orioles in particular, love the edge habitat that the farm creates, and they can often be seen gregariously chasing each other across the airspace directly over the farm fields. In winter, they seek similar open habitat on shade-grown coffee farms in the tropics.

And let’s not forget the year-round residents of Rushton! Between-year recaptures included 50% of Tufted Titmice, 75% of Northern Cardinals, and 100% of Carolina Chickadees.

Spring banding ended with a warm spell that brought the highest diversity of the season, including an old Indigo Bunting originally banded in 2019, and a surprise Yellow-breasted Chat! Normally fairly flamboyant with an odd series of croaks, whistles, and short repeated phrases, this chat wasn’t chatting at all. If we had not caught the bird in a net, most likely we never would have known it was there. As one of our “life is messy” species, early successional shrub habitat (often perceived as messy) is its preference, which we embrace wholeheartedly at Rushton.

MAPS 2024

When we report the total number of birds each year, we often only report the total number of new birds, excluding recaptures. During migration, the recaptured birds are most often the same birds we banded within that season. The data we are acquiring from such recaptures is mostly how long the bird stayed at Rushton, or if it gained weight for its migratory journey, which can both be indicators of habitat quality. For example, one voracious Veery was determined to have gained 13% of its body weight in seven days of dining from the Rushton all-you-can-eat buffet! However, recaptures can be broken down into two categories: birds that we banded within that same season or year, and banded birds that are returning to Rushton from a previous year.

During the breeding season, songbirds often show high site fidelity, meaning that they will return to the same site from year to year to breed. They are more likely to do this if they were successful at breeding the previous year. This year, after 14 years of MAPS banding at Rushton Woods, we became concerned that some of our most common breeding birds were declining, like the Veery. However, after a closer look at the data, we can see that numbers of most of our birds are stable or showing normal fluctuations; we just had to take into account the birds that are returning each year!

Nearly 30% of our MAPS birds return each year to breed at Rushton Woods. Our top five most common birds captured are Gray Catbird, Common Yellowthroat, Ovenbird, Veery, and Wood Thrush (accounting for 75% of all birds banded). While it varies from year to year, we see a similar average rate of 30% returning birds of our top five species. Figure 1 shows the percent of return birds for each of the top five species each year. You can see that Common Yellowthroat, Ovenbird, and Veery are consistently returning at the highest rates; in some years as high as 66% of the birds of these three species are returning! Interestingly, Ovenbird and Veery are the only two ground nesters in this group, and both have high return rates. In particular, after thirteen years, an average of 42.5% of our total Veery population have returned to breed at Rushton!   

Fall 2024

This fall was truly surreal. Typically our busiest banding season, we look forward to the waves of species groups coming in from week to week (Figure 2). This season started out slow and never really picked up like it normally does in September. We were seeing the usual suspects, but not the usual numbers of individuals. Where did all the catbirds go? We had the lowest capture rates ever documented of Gray Catbirds in spring and fall. This particularly concerning fall saw a 72% decrease in catbirds from last fall and a 75% decrease from our 14-year average.

Chimney Swifts (Chaetura pelagica) are fascinating small birds with a cigar-shaped body and long narrow wings, known for their distinctive agile flight and unique nesting habits. Historically, these birds nested in hollow trees, but as human development progressed, they adapted to using chimneys and are now dependent on man-made structures. Unfortunately, modern building designs and habitat loss have significantly reduced Chimney Swift populations with their current conservation status listed as near threatened. Within the past 20 years, there has been a movement to cap chimneys or line them with metal, thus preventing access for the swifts. Additionally, old buildings with suitable chimneys are increasingly demolished or sealed, further reducing available nesting sites. Climate change further complicates their survival by altering insect populations, their primary food source, and increasing extreme weather events that can destroy nesting sites.

To counteract these challenges, building and installing Chimney Swift nest boxes, or towers, is essential for conserving this species. These nest boxes provide safe, suitable nesting and roosting sites. These towers should be at least 12 to 15 feet tall with a minimum width and depth of 14 inches on each side, using durable materials like treated wood or concrete to ensure longevity. The interior should have a rough surface to help swifts grip and build their nests. Ideal locations include backyards, parks, schoolyards, and other community spaces.

Pennsylvania Game Commission (PGC), is working with conservation partners to build Chimney Swift towers and are working on a documentary to educate landowners about how these can fit into their landscape. PGC Education Specialist and filmographer, Tracy Gaziano, is gathering this information and working with partners such as WCT to help conserve this declining species. WCT now has four towers, all of which have had successful breeding pairs year after year since their installation. Terry Decker from Oak Tree Landscaping built the three original towers starting in 2018 (figure 1), and Sean Hetzel, a local Eagle Scout, recently added a modern tower (figure 2). Terry donated his time and bucket truck this summer to provide a bird’s eye view to the nests so Tracy could get great photos and video of their nests.

Although building a Chimney Swift tower appears to be a daunting task, there are many resources on-line to provide the plans and methods. PGC is building towers in desirable locations, but local builders could follow the nest box plans. The tower must be secured to a foundation, ensuring it is stable and upright, while regular inspections are recommended before the breeding season to ensure it is in good condition and free from debris. It is also essential to monitor the tower during the breeding season to assess the nest box’s success. Nest boxes offer a predator-free environment, help mitigate habitat loss, and contribute to the conservation of Chimney Swifts. They also provide educational opportunities, raising awareness about these birds and their conservation among local communities. Resources for building Chimney Swift nest boxes include the Chimney Swift Conservation Association and Cornell Lab of Ornithology.

Tracy Gaziano with The Pennsylvania Game Commission and Terry Decker with Oak Tree Landscaping working together to collect footage of the nestlings.

By building and installing Chimney Swift nest boxes, we can play a crucial role in protecting and supporting these unique birds, ensuring they continue to grace our skies for generations to come.

On May 15, 2024 the Cornell Lab of Ornithology awarded Willistown Conservation Trust (WCT) $25,000 through the Land Trust Bird Conservation Initiative. This grant marks the second subsequent round of funding from Cornell Lab in support of the project, Finding Common Ground to Reverse the Decline of Grassland Birds Across a Working Landscape. This year-long project will be conducted between May 22, 2024 and May 21, 2025 in an effort to enroll at least 1,500 acres of privately held lands in delayed-mow management and monitor those fields to measure productivity, among other important objectives.

Grassland Birds are experiencing the largest land bird declines of any habitat group.
Scientists estimate populations of many bird species are just half of what they were in 1970. Two-thirds of grassland birds have experienced population declines, and one-quarter of these species, including the beloved Bobolink, are Tipping Point Species. From 1970 to 2019, Tipping Point species have experienced population losses of 50%, and, in the next 50 years, they are on track to lose another 50%.

The good news is losses of these birds can be reversed. Locally, we can help these birds before they are endangered through voluntary cooperation powered by partnerships among landowners, farmers, and conservation organizations. In 2022 WCT launched the Grassland Bird Collaboration (GBC) to establish official partnerships and utilize years of grassland bird research to inform best practices in the field to support bird populations. 

Our goal is to create a grassland bird conservation area made up of working landscapes and existing nature preserves in southern Chester County’s preservation greenbelt. These lands will serve as a focal area for conservation efforts where partners work together to address the issues affecting declining grassland species while appreciating and promoting the economic and aesthetic values of the agricultural lands in the conservation area.

In addition to enrolling privately held lands into delayed mow-management, this project will focus on collaborating with other enrolled properties to host grassland bird walks, professionally monitor and record collected data for further research, observe the mutual benefits of the avian-agricultural system and extend sustainable farming practice resources to farmers and landowners to expand “bird-friendly” practices in the program area. For additional information about the Grassland Bird Collaboration please contact Lisa Kiziuk (lkr@wctrust.org) or Zoe Warner (zmw@wctrust.org) or visit https://wctrust.org/the-grassland-bird-collaboration/.

By Alison Fetterman, Avian Conservation Biologist and Blake Goll, Education Programs Manager

Introduction | As field biologists living in a human dominated world where wildlife populations have plummeted by 70% in the past 50 years — and birds, in particular, by 30% — the more biodiversity we can record, the higher our hopes. It turns out, bird banders are not alone in this innate need for birds. A recent study by the German Center for Integrative Biodiversity Research shows that connection to nature, especially bird life, is directly linked to our sense of wellbeing. The study linked greater bird diversity to increased life satisfaction for more than 26,000 people; the people who lived near natural areas with a greater diversity of birds were significantly happier.

But birds do more than simply enrich our lives. They are the ultimate environmental bellwether whose population changes can underscore global and local issues ranging from climate change to habitat degradation. At Rushton Woods Preserve and Farm, we strive to model restored landscapes where both people and wildlife thrive. Over 30,000 pounds of chemical-free food is produced annually on just a few acres of regeneratively farmed land within an 86-acre nature preserve. A total of 19,921 birds of 104 species have been documented (through banding) using the Preserve since 2010 (Figure 1).

Here, food and feathers exist in harmony; instead of dominating the land with sights set only on profit, the land is honored with our sights set on feeding the community while bolstering biodiversity and ecosystem health. Birds are free to use the farm to refuel during migration or even nest during breeding, and the farm, in turn, benefits from ecosystem services like pollination and pest control, thanks to the preservation of adjacent native meadows and shrublands. It is in these shrublands where we conduct our migration banding efforts at Rushton Woods Banding Station (RWBS).

SPRING MIGRATION | Aside from the first unseasonably warm week in April, it was largely a cold spring lacking in the southerly winds required to drive migratory birds north to their breeding grounds in a synchronous manner. We experienced our lowest migration capture in our station’s 14 year history: 237 total new birds. Many factors can affect capture including habitat change, global population declines, weather, and effort. Because we only band three days per week and spring migration is rapid (with birds racing to be the first back to the best breeding grounds), it is possible we missed some of the waves of birds moving through. Nonetheless, the data did show delays in spring migration with the highest season capture (49 new birds) occurring on May 9th, one of the latest peaks experienced at RWBS.

Nonetheless, the Northeast’s dazzling diversity of warblers is never more evident than in May when they’ve donned their nuptial plumages and put forth their unique and soulful notes into the collective spring orchestra. Our catch included the wide-eyed Canada Warbler with her bohemian necklace of onyx, the zebra striped Black-and-white Warbler, the calico streaked Cape May Warbler with his striking orange face, the Magnolia Warbler with his stunning black mask and bright yellow throat, and the steel blue cloaked Black-throated Blue Warbler. Few artists could fabricate such a kaleidoscope of patterns and colors.

Some birds return to us year after year, exemplifying the importance of protected habitat, like Rushton Woods Preserve, as places birds can count on for refueling, overwintering, or nesting. One White-throated Sparrow, for example, was originally banded at Rushton in 2021, caught again in spring of 2022, and again in April of 2023. This bird likely overwinters at Rushton each year before returning to its northern breeding grounds in New England or Canada.

Baltimore Orioles are the impresarios of our hedgerows, belting out their whistle songs from the treetops once they return in May. Last spring we captured an adult male that we had originally banded in 2018, making him at least 7 years old! Each spring, he dutifully returns to Rushton to breed after overwintering in similar habitat in the tropics — quite possibly that offered by shade grown coffee farms — relying on the diversity of canopy structure offered by regenerative agricultural practices.

SUMMER BREEDING | Summer is the time when our banders retreat to the coolness of Rushton Woods to study the breeding populations of birds in our woodland for a national effort called MAPS (Monitoring Avian Productivity and Survivorship).

After a low catch of birds in 2022, we were up to a nearly all time high in 2023 with 155 birds of 17 species. We caught a record number of Gray Catbird (59), Carolina Wren (6) and Red-eyed Vireo (7). The former is unexpected as vireos are common breeders of the canopy where we cannot place our nets.

Another tree-top dweller that surprised us last summer was an adult female Scarlet Tanager. As we banded this beautiful yellow bird, her scarlet-colored mate impatiently scolded us from an uncharacteristically low perch. Though we hear males singing each summer, we were unable to fully confirm breeding success until observing this female in hand with a full brood patch (indicating a nest with young). As a State Responsibility Species, Pennsylvania plays a significant role in sustaining the global security of Scarlet Tanagers by hosting 10% of their breeding population.

FALL MIGRATION | The fall procession of southbound neotropical migrants is slow and steady — with birds no bigger than a third of an ounce winging their way along ancient pathways stretching for hundreds of miles in the star studded dark of night. This goes on for almost a month longer than the hurried spring migration, creating multiple waves of species moving through (Figure 2). Like clockwork, as the radiance of the goldenrod fades and the leaves become one with the autumn wind, the bounty of bright warblers morphs into the more muted earth tones of sparrows and kinglets.

It was a relatively warm fall with the first week of September bringing an unprecedented heat wave during which temperatures soared dangerously high for safely operating mist nets. The health of the birds is our highest priority, so the station was closed for the entire week on account of heat for the first time ever. Once the season got underway, however, it turned out to be a successful one with the exception of a record low number of Ovenbirds (only one individual compared to our usual 15-30).

The catch included record high counts for Ruby-crowned Kinglet (113), Swamp Sparrow (33), Nashville Warbler (6), and Hermit Thrush (55). As one of the most intricate songsters of the bird world, the Hermit Thrush’s reedy tremolo echoes throughout woodlands of the mountains and the north. This shy bird is the hardiest of our brown thrushes and least dependent on tropical forests for wintering, often seen throughout the winter in our own PA backyards. For this reason, it is separated from the earlier migrating thrushes in the wave graph (Figure 2).

Birders also help us document the species waves of migration. Last September, a local birder captured a spectacular sight: a Cape May Warbler feasting on cherry tomato juice at Rushton Farm! Most warblers primarily eat insects, but this striped sprite has a specialized, slightly decurved bill that allows it to also probe flowers and fruits for nectar; their long, curled tongues allow them to imbibe from ambrosias not available to other birds —from black cherry and tulip poplar flowers to grapes and tomatoes.

Back at the banding station, we had some rare captures last fall including a Mourning Warbler (only the fourth ever for our banding station) as well as our very first Orange-crowned Warbler in late October.
Orange-crowned Warblers are uncommon in the eastern United States during migration. As one might expect from the similarities of its fine, pointed bill to that of a Cape May Warbler, the Orange-crowned can also feed on nectar and sap, as well as berries and insects. In the west, they are known to dine from Red-naped Sapsucker wells! Its varied diet allows the boreal-nesting Orange-crowned to travel south later than other warblers.

The highest catch of the fall season occurred following a cold front on October 24th with a total of 126 birds of 17 species, including a Winter Wren. This magnificent little creature is a brown ball of plain, speckled feathers that has been gifted with one of the most stunningly spirited songs of the bird world — the ebullience of which has earned him the title of “heart of the forest.” Per unit weight, the Winter Wren actually delivers its song with ten times more power than a crowing rooster!

Last but not least, we ended the season with the first Fox Sparrow since 2017. Unmatched in elegance, the Fox Sparrow is a true bird of the north, nesting from Alaska east to northern Quebec and the Maritimes. Homeowners can provide suitable overwintering habitat for Fox Sparrows by creating or preserving thickets, early successional shrublands, and second-growth forest.

Conclusion | We do not take the temporary care of such wild beauty lightly, and it is the transient presence of these incredible trans-continental animals in our little preserve that casts a hushed reverence on banders as they begin their work in the mystical pre-dawn.

Bird banding is a powerful tool in bird conservation, allowing us to study species abundance and diversity, population patterns, survivorship, and productivity of migratory and breeding birds as well as ecosystem health. For a more in depth look to view Rushton Woods Banding Station (RWBS) Songbird Banding Report 2010-2023 click here.