New Jersey Osprey Project // Nest Monitoring Portal

Survey methods remained the same between the 1970s and 2009, which consisted of aerial censuses conducted by helicopter (1993–2009) and fixed-wing aircraft prior to 1993. Surveys were performed annually along the coast until 1988, biennially in 1988-2003, and then triennially in 2003-2009. The surveys were conducted twice each season: once in mid-May when ospreys were incubating, and again in mid-June when most nests had young visible in nests. The use of helicopters for aerial surveys allowed efficient monitoring of most coastal colonies, from near Manasquan Reservoir south to Cape May and then west along the Delaware Bayshore to Salem.

These surveys made it possible to estimate the total size, distribution and nest success of ospreys by determining the number of occupied nests and those that successfully produced young. Some of the most densely populated nesting colonies were surveyed by staff and dedicated volunteers who visited nests by boat or on foot. Data collected during these surveys have been used to estimate the overall health of the state population by measuring their productivity (# young produced/active nest). Colonies that have been surveyed for decades include Sandy Hook (Gateway NRA), Barnegat Bay ( including Sedge Islands WMA and Island Beach State Park); Tuckerton – Great Bay; Avalon – Stone Harbor, Wildwood and the Maurice River. During ground surveys, young were banded for future tracking by licensed bird banders. Nests that were abandoned or empty during ground surveys were recorded, but the combination of aerial and ground survey data helped estimate actual failed attempts. Since 2009, no aerial surveys have been conducted to determine the overall size and health of the osprey population in New Jersey. Instead, all osprey nests have been mapped online, on www.Osprey-Watch.org, a global osprey watching community, allowing biologists to engage with citizen scientists to record nesting activity. This was the first time that nests for a threatened species were publicly mapped online, encouraging the public to seek them out. We believed it could be successful, as ospreys are a highly visible species with nests located near residential development along the coast.

Today, ground-based nest surveys are conducted by staff and specially trained volunteers primarily in late June and early July, when ospreys have nestlings that are typically around 3-4 weeks old. During this time they are usually highly visible, yet unable to fly. This is also the perfect age when they can be banded for future tracking. Like the historic surveys, all major colonies from Point Pleasant south to Cape May and west along the Delaware Bayshore are surveyed (see table 1 for a list of all colonies). Other regions are surveyed by partners, consultants and many volunteer “Osprey Watchers” who report nest observations online on Osprey-Watch.org.

Most osprey colonies are surveyed by boat, since most nests on wood platforms are located within saltmarsh habitat. Nest occupancy is noted by the presence or absence of adults. To determine the outcome, nests are either climbed via ladder, viewed with a mirror/GoPro on an extendable pole, camera with telephoto lens, or with a sUAS/drone (under permit). In more recent years the use of a GoPro is the primary means by project staff, as it reduces time spent at nests, which reduces disturbance to adults. However, nests with visible plastic marine debris are climbed to remove that risk of suffocation or entanglement. Nests are also climbed when the young are old enough to band with aluminum USGS bird bands (and red auxiliary bands on Barnegat Bay). Lastly, at nests where we band young, typically fresh frozen menhaden are left to offset disturbance to adults and young.

When first entering a colony and nest, it is viewed from a distance with optics. This is done to first determine occupancy. If adults are present then the nest is considered occupied. Their behavior is noted during this time. If an adult is sitting low in the nest with a flat back, then they are likely incubating eggs. If they are standing beside the nest bowl (shading young) or without a flat back, then they likely have young. When approaching a nest, if adults fly off their nest and actively defend it, then that is usually a sign that young are present. The presence of young is confirmed by the visual methods stated above. Documenting nest failures is based on behavior of the adults and inspecting nests for signs of current-season use.

As in recent years, we were able to determine more accurate nest outcomes by conducting several early (incubation) and follow up (pre-fledgling age) surveys.