Welcome back to the second season of American Oystercatcher monitoring on New Jersey’s Delaware Bay beaches! CWF, and our partners at the Wetlands Institute and USFWS, have returned to the Bayshore to continue our research project funded by the National Fish and Wildlife Foundation (NFWF). Last year, the CWF-led team surveyed 29 miles of Bayshore beaches, monitored 19 nesting pairs, banded seven adults and four chicks, and conducted invasive species removal. This year, we’re excited to build on that progress and learn more about this previously understudied oystercatcher population.
This year was an especially challenging one for beach nesting birds in New Jersey. Most of the species fared poorly on a statewide basis, and even though they can withstand periodic down years, several trends are worrisome to biologists and wildlife managers.
The state’s piping plover breeding population remained the same as last year with 118 pairs, which is also about the same as the long-term average since federal listing. However, productivity was just 0.53 chicks fledged per pair, the second lowest since federal listing and well below the levels believed necessary to grow the population. Of particular concern, productivity has been low for three consecutive years after a number of years of above average success. Productivity is one of the main drivers of population (up or down) and small populations are especially sensitive to even small changes, so it is expected that the population is likely to drop over the next few years, further stagnating plover recovery in the state.
Meanwhile, there was a record number (53) of breeding pairs of piping plovers at Holgate, a unit of the Edwin B. Forsythe National Wildlife Refuge, that is monitored by CWF through a cooperative agreement with the Refuge. This positive trend, almost a four-fold increase has occurred since Superstorm Sandy enhanced the habitat for plovers at the site, has been an ongoing highlight for the state in recent years. Nonetheless, it has not been accompanied by similar increases elsewhere in the state, so it has not led to any statewide recovery. Productivity for the large concentration of piping plovers at Holgate was above the statewide average in 2023 but the lowest level over the past decade, so it was also a down year for this site, where expectations typically run high that it will help boost statewide productivity.
This marked the second year that CWF worked in close partnership with New Jersey Fish and Wildlife and Edwin B. Forsythe National Wildlife Refuge (EBF) to monitor and manage birds on Horseshoe Island. The island, located just offshore on the southern edge of the Little Egg Inlet, has quickly become one of the most important sites for beach nesting birds in the state, as well as a critical resting and feeding site for migratory shorebirds.
Horseshoe Island hosted the state’s largest black skimmer (state endangered) colony this year with just over 1400 total adults or about 700 pairs. Although flooding and some avian predators impacted the overall nesting success at the island, at least 225 skimmer chicks “fledged” from the site. Horseshoe’s skimmer fledglings, along with those from nearby Holgate, a unit of EBF, and especially from Stone Harbor Point in Cape May County, made 2023 a moderately good productivity year for black skimmers in New Jersey.
A small portion of the black skimmer and royal tern colony on Horseshoe Island. Photo credit: Teri Bowers
This past winter, CWF announced a new project designed to study and monitor the population of American oystercatchers breeding along the New Jersey side of the Delaware Bay. In addition to locating nesting pairs and tracking their success, our goal is to better understand how oystercatchers utilize the bayshore habitats and what factors threaten their productivity. The data we gather with our partners at The Wetlands Institute and U.S. Fish and Wildlife Service will be used to inform future management decisions. We spent the past few months working hard to conduct the project’s first season of monitoring, and we are happy to say that we have made significant progress in beginning to unravel the mysteries surrounding this understudied population.
Delaware Bay American oystercatcher study area. Most oystercatcher pairs this season were concentrated in the bay beaches between Stipson Island and Heislerville WMA.
Since so little is known about this subpopulation of oystercatchers, we had a lot of ground to cover in our first season of fieldwork. First, we had to locate any breeding oystercatcher pairs across 35 sites spanning approximately 45 miles of bayshore from Cape May Point to Sea Breeze. Luckily, we had a head-start based on a preliminary census survey from 2021 that documented some already existing pairs as well as some sites with potentially suitable nesting habitat. We were also fortunate to have a dedicated seasonal technician assisting with the heavy workload. That said, figuring out how to access many of these sites was definitely a learning curve. We quickly discovered that many beaches were only reachable by boat or kayak and only during a narrow window of tide and wind conditions. Other sites were walkable, but only at peak low tides, which meant our surveys couldn’t take too long without risking becoming stranded by the rising tide.
With about 50 pairs of both piping plovers and American oystercatchers nesting this year at Holgate, a unit of the Edwin B. Forsythe NWR, CWF’s seasonal staff that monitors breeding activity for the Refuge has been working at a non-stop pace. We asked them to take a short break from their field tasks to reflect on their season, for some this is their first experience with beach nesting birds. Specifically, they were asked about their favorite and most surprising things about the birds, so far. Read their responses below, including a little twist of the “least favorite” thing in one case.
CWF’s 2023 beach nesting bird monitoring crew for Edwin B. Forsythe NWR and Horseshoe Island. Morgan Phillips, Gianna Canale, Audrey Randazzo, Amy Kopec, Dakota Bell (l to r).
Horseshoe Island, located just offshore of Little Beach on the southern edge of the Little Egg Inlet, is teeming with wildlife again this year. Last year, under a five-year Management Rights Agreement secured from the state’s Tidelands Resource Council, the site was closed to the public from March 1- September 30 to benefit wildlife, in particular endangered and at-risk beach nesting birds and migratory shorebirds. The seasonal public closure of the island and its surrounding tidal areas is in place again this season.
Aerial view of Horseshoe Island Courtesy of New Jersey Fish and Wildlife
Earlier this summer, it was announced that the annual range-wide American oystercatcher meeting would be held in December on the Gulf Coast of Florida near Naples. Thrilled to finally be attending in-person after several pandemic years of virtual meetings, my mind immediately pivoted to what other nearby nature sites I could also visit. Or more specifically and not too surprising for those that know me…where could I go to view wintering piping plovers.
In late September, Hurricane Ian made a direct landing in this region of Florida. The meeting had to be scuttled, relocated to the Georgia coast. And just like that, my “add-on” plans – I had arranged a short trip to Outback Key about two hours north of the meeting – fell off the itinerary.
Or maybe not. Georgia borders Florida, right? Six hours of driving for a chance to see 50-60 piping plovers in one spot is reasonable, right? Did I mention at least one New Jersey breeder winters at the site?
So as soon as the oystercatcher meeting wrapped at mid-day, I found myself in a car, along with fellow CWF Biologist Emmy Casper, hurtling toward St. Petersburg, Florida. We arrived at nightfall, woke in what felt like a flash, so we could wait in a line of cars, still in the dark, for Fort DeSoto County Park to open at 7 am. We had a very narrow window for our visit with the morning low tide being optimal shorebird viewing at Outback Key and because we had mid-day flights home.
American oystercatcher foraging for oysters along the Delaware Bay. Photo credit: Meghan Kolk.
The Delaware Bay is well known for the spectacular phenomenon of spawning horseshoe crabs and migrating red knots every May, but in recent years the American oystercatchers (Haematopus palliatus) have also discovered the allure of the Bayshore and made it their home. American oystercatchers, a State Species of Special Concern, have been monitored and managed by CWF and the NJDFW’s Endangered and Non-game Species Program along the Atlantic coast beaches for nearly two decades, resulting in a steady population increase. However, the population that breeds along the Bayshore, first documented in 2016, has not received the same attention and had never been fully surveyed until this year.
CWF’s interest in this newly discovered population led to a small pilot study of a few known breeding pairs in 2018. Then this past May, we launched a bay-wide survey of the sandy beaches of the New Jersey side of the Bay from Cape May Point up to Seabreeze, the northernmost beach in Cumberland County. The purpose of the bay-wide survey is to determine a baseline of the number and distribution of breeding pairs along the Bayshore. The data gathered from this survey will add to the Statewide population estimate and help determine the amount of time and funding needed to fully monitor and manage the Bay’s population. More monitoring will be necessary to assess risk factors and reproductive success. Reproductive success can then be maximized by managing for risk factors such human disturbance, predation and tidal flooding.
This survey was made possible due to the efforts of dedicated volunteers and could not have been completed without their help. Unlike the Atlantic coast, the Bayshore beaches are often difficult to access, and many can only be reached by boat, making this survey more challenging. In fact, two sites that we planned to survey proved to be too difficult to reach and were skipped for this year. Each of the 33 remaining sites were surveyed just once within a specific timeframe, giving only a snapshot of the breeding season. We hope to be able to collect much more information in the future when more funding for this project is available. Based on the survey that was conducted, 13 pairs were documented at 8 different sites and 8 nests were documented at 5 different sites.
In addition to the formal survey, I was able to collect some observations as I spent every day in May on the Bay working with red knots. I took notice of the prey items that the oystercatchers were choosing. I often observed them feasting on oysters, which were plucked off exposed rubble at low tide. They also spent time at the man-made oyster reefs that were constructed at several beaches to act as breakwaters to slow the erosion of beaches. They also favored ribbed mussel beds, which become exposed as the tide recedes. The most interesting foraging behavior I witnessed was an oystercatcher plucking a fresh slipper shell off a horseshoe crab as it came to shore to spawn. It seems the Bay offers a variety of good food sources for a bird that mainly preys on bivalve mollusks.
I also noticed that flocks of up to 11 oystercatchers were traveling together up and down the Bayshore. This is a peculiar behavior since oystercatchers are highly territorial during the breeding season and are typically only seen in flocks once the breeding season is over. Could it be that the Bayshore is a popular spot for non-breeding young adults to hang out?
So much more research is needed to answer the many questions we have about the mysterious Bayshore oystercatchers.
A piping plover chick tests out its wings. Photo courtesy of Bill Dalton.
A new report from Conserve Wildlife Foundation and the New Jersey Division of Fish and Wildlife shows that the state’s piping plover population increased in 2019, leading to cautious optimism for the birds’ long term prospects. The piping plover is listed as threatened federally and endangered in New Jersey.
One hundred fourteen pairs of piping plovers nested in New Jersey in 2019, a 19% increase over 2018’s 96 pairs. The 2019 population is slightly below the long-term average of 117 pairs and well below the peak of 144 pairs in 2003.
Piping plover productivity, measured by the number of chicks who survive until their first flight (or fledging), dropped from 1.51 in 2018 to 1.24 in 2019, and was the lowest seen in the last six years, but remains above the long-term average of 1.3.
Many piping plover and American oystercatcher pairs have been busy laying their eggs over the last few weeks. As beach nesting bird biologists, we invest a lot of time into every pair at our sites. We revel in their successes and feel defeated at their losses. Unfortunately, many nests did not fare well in the April 25th Nor’easter that was coupled with new moon tides. Luckily, it is early enough in the season that all of them have begun, or will soon begin, attempting new nests.
The breeding habitat of the American oystercatcher in New Jersey consists of coastal beaches, inlet systems, and salt marshes. Population estimates in New Jersey suggest 350-400 breeding pairs can be found here from March through August. Much of the monitoring and research done with American oystercatchers in New Jersey takes place on the coastal beaches where other beach nesting birds, such as piping plovers, least terns and black skimmers, are found. In 2016, more than 120 breeding pairs of beach nesting American oystercatchers successfully fledged 83 chicks. This was an especially productive year for those pairs and productivity levels were well above the target goal of .5 chicks per pair.
Photo courtesy of Sam Galick.
Oystercatchers arrive back on their breeding grounds here in New Jersey in early March to set up breeding territories and begin nesting. Once paired up, adults typically lay one to three eggs. Both the male and female will take turns incubating the nest for 28 days. Once chicks hatch, they are semi-precocial, which means they are born in an advanced state, but are still reliant on adults for food and protection. Oystercatcher chicks are fledged (or able to fly) 35 days after hatching. After fledging, most Oystercatchers migrate to the southeast, but a wintering population does remain here in New Jersey.
American oystercatchers are listed as a Species of Special Concern in New Jersey. A “Species of Special Concern” is a status determined by the New Jersey Division of Fish & Wildlife and applies to species that have an inherent threat to their population or have evidence of recent population declines. Since American oystercatchers share the same habitat as other endangered or threatened beach nesting birds (piping plovers, least terns, and black skimmers), they also share the same threats to their nests and young. Human disturbance, a host of predators, and flooding events, such as the one that took place last week, are just some of the many threats beach nesting birds face daily.
The Conserve Wildlife Foundation of New Jersey has long partnered with the New Jersey Division of Fish and Wildlife’s Endangered and Nongame Species program in the monitoring and management of New Jersey’s endangered beach nesting birds. Fencing and signage are placed in nesting areas to alert beachgoers to the presence of nesting American oystercatchers and other beach nesting birds. Throughout the summer, CWFNJ and partners will be out on the beaches monitoring and collecting data that will be used to track population trends and identify threats to oystercatchers and their young.
Emily Heiser is a wildlife biologist for Conserve Wildlife Foundation of New Jersey.
