The Results Are In!!

Mild weather helps boost Osprey population

This year was the most productive year for ospreys in the projects history. The reproductive rate was about 2 young per active nest (an all time high for the project). No doubt the calm weather played an important role this year. Calm weather makes prey easier for ospreys to find, especially fluke and flounder, one of their main prey sources. More food means larger broods. Nests with three, even four young were quite common this year.

An adult osprey calls to defend its offspring at a nest in Mantoloking, NJ. © Eric Sambol

Of the 308 active nests (where the outcome was known) 36% of nests had 3 young, 33% had 2 young, and 14% had one young. Only 11% observed had failed to produce young. For comparison, in 2006, 14% failed and in 2003, 46% failed. 2003 was the worst year for ospreys in recent history (to read the 2003 newsletter, click here). Weather played a large factor that year. Check out one of my previous posts for more on weather and production. To read the full results from the 2010 survey, click here.


Thank you to all our volunteers who braved the scorching heat this summer to collect data to help us manage and monitor the population! And thank you to all donors and supporters of the project! With out your support and contributions our work would not be possible!

Fall is for ...

Platform Repairs and Installations

Fall is upon us and while ospreys are headed south or already in their wintering areas I am still keeping busy. This past Sunday I helped a Boy Scout with his Eagle Scout Project to install 4 nesting platforms. The platforms were installed near Ocean City and Somers Point. All platforms were placed on public property, state and locally owned. Two platforms were placed near duck blinds where ospreys nested in the past two years. Both nests failed to produce young. When ospreys nest on duck blinds their eggs and young are very vulnerable to predation from ground predators, like raccoons. The platforms we placed are specifically designed for ospreys and have a sleeve-type predator guards to deter predators from climbing up into the nest. 

Scouts from Troop 79 help Eagle Scout Holden Gentilini raise a platform. © Ben Wurst

One of the other two platforms was used to replace an old platform that has never been used by ospreys. It was large enough but very unstable. The main pole was only a 4x4". We only use 6x6" poles for our platforms. They have been shown to withstand strong Nor'easters we get in late winter and can easily support a biologist when they climb to survey and band the young in late June each year. The last platform was installed in a new location that is close to where a local dispute has occurred over a group that installed a platform on private property. The property owner removed the platform earlier this year just as ospreys were returning to nest in early April (also the time when it is illegal to remove a nesting platform). This platform will hopefully attract that pair since it is not far away and is in my opinion in a much more suitable location away from any human disturbance. 

Holden (left) finishes back-filling the hole on the final platform.

© Ben Wurst

Interesting Band Recovery

Juvenile flies north instead of south

Today I received notification that a young osprey I banded on June 30th in Little Egg Harbor was found dead on August 25th 5 miles NW of Chenango Forks, NY. The banding recovery data indicated that the bird was found in a homeowners property by her dog. This is not entirely uncommon for juveniles to fly north then turn around and fly south to their wintering areas. In 2009, an osprey named "Hix" that was tagged and fitted with a satelite transmitter traveled north from southern Mass. to Maine after fledging. Unfortunately, he did not survive either.

 

Weather & Climate

How it Affects Osprey Reproduction

2003 was one of the worst year's for osprey in New Jersey. Here is an excerpt from the 2003 New Jersey Osprey Project Newsletter:

"While the statewide average production was 0.86 young per active nest, it was somewhat better in Delaware Bay nests, at 1.09, than in Atlantic Coast nests, 0.73.  Productivity was depressed at all study areas, however, from Raritan Bay to Cape May to Delaware Bay.  Overall, productivity was down 27% from the 1997-2002 average of 1.18 young per nest.  This year it hovered close to the 0.80 young per nest considered necessary to maintain a population.

The most likely cause of this year’s nest failures is the weather during April and May, when ospreys were incubating and just hatching.  It was unusually cool and wet, and those conditions can have several implications for ospreys:  the high precipitation may have delayed fish migration and spawning, making prey harder to find; it may also have increased water turbidity, making it more difficult for ospreys to see fish.  As ospreys spent more time hunting with less success, their incubating partners may have been forced to leave the nest – exposing eggs or young chicks to weather and predators – to hunt for themselves.  In addition, we found that many young nestlings died when they were just two to three weeks old in June and early July, most from starvation, so the effects of the cool spring were far-reaching.  Unlike previous years when nest success declined in one region or another (primarily the Atlantic Coast), this year’s problems were statewide, which supports the theory that weather was the predominant cause." -- Kathleen Clark, Principal Zoologist, Endangered and Nongame Species Program.

Courtesy NJ Office of the State Climatologist.

No doubt we all know we had a HOT summer! It seems to have helped boost the osprey populations reproductive rate in all areas from Raritan Bay south to Cape May and west to Salem County, except for one area, Sedge Islands WMA. Its unclear why the Sedge population did not do as well this year. The productivity at Sedge varies from year to year, while the number of active nests has remained very similar (between 21 to 28 active nests from 2005 to 2010). Productivity peaked in 2008 and was at its lowest in 2003.

Courtesy NJ Office of the State Climatologist.

 A warm and dry climate will make nesting attempts more successful, while calm conditions will make foraging attempts more successful. Many bald eagle nests failed this year most likely from the wet conditions in February and March (when young nestlings are more vulnerable to harsh weather). Timing is everything. Osprey feed a variety of species of fish. Whatever is plentiful. This year menhaden was very plentiful off-shore. Boats from New England even came down to catch it for use as bait in the lobster fishery. Calm weather probably made it much easier to see and catch fish this year. Turbidity in water in calm weather is reduced so in-shore and off-shore waters were pretty clear. To be able to successfully raise young, male osprey need to supply a large amount of food to the female from coopulation through to when the young fledge (from early April to early-mid July). They need about 6 lbs. of fish a day to sustain themselves. Of 304 nests that were occupied (with a known outcome) 114 of them produced 3 or more young. Three nests produced 4 young. Outstanding results that will be summarized in the 2010 New Jersey Osprey Project Newsletter, which I'll be working on over the next week.

Osprey nestling giving Eric Sambol the stare down. © Eric Sambol.

On another note, we hit a whole bunch of milestones this year! Here's one: Volunteers and biologists surveyed more nests this year than any other year (when not conducting an aerial survey). 350 nests were observed as being occupied by a pair of ospreys. Previously the highest count was 288 nests. 70% of the population was covered this year! I just want to thank all our awesome volunteers who access many of these nests to band the young for future tracking and to all the other volunteers who report new nests in areas we don't routinely survey! Thanks!

Photo from the Field

I had the pleasure of receiving this photo from Joe Orlando shortly after we installed this platform on August 13th. Joe donated to have this platform placed near his house in Ocean City. His donation goes far beyond this single platform. It will be used to repair and replace other platforms to support our goals of helping the state population recover to historic levels (pre-DDT). A few days after we installed the platform Joe sent me this photo. I was happy to see a pair of adults that were already starting to place some nesting material in the platform before they fly south to their wintering areas. This is a good sign that this pair might return to nest on this platform next year! 

Thanks for the donation and the photo Joe!

A pair of ospreys instantly take to a new platform installed on August 13th in Ocean City. Photo by Joe Orlando.

Osprey Surveys Begin!

On June 21st the first of many osprey surveys began. The surveys are performed every year to help determine the overall health of the population. Most surveyors are volunteers who commit many hours of their personal time to helping us monitor the population. USGS leg bands are placed on the young that are produced. The bands gather valuable data. They help us understand where ospreys migrate and winter, their survival rates, and how behave.

An adult leaves a nest as I approach by boat in Absecon.

By this time, many osprey young are 3-4 weeks old. This is when they can be banded. Not all ospreys begin nesting at the same time, so some adults are still incubating or have young that are only hatchings to two week old young. Generally, the more experienced adults start earlier and are more successful at raising those young. Younger adults start later and have a far less chance of successfully raising young. 

Volunteer surveyors cover all major nesting colonies, from Sandy Hook south to Alloway's Creek along the Delaware Bay. The major nesting colonies are Sandy Hook, Barnegat Bay, Sedge Island, Great Bay, Margate/Ventnor/OC, Great Egg Harbor River, Stone Harbor, Avalon, Wildwood, and the Maurice River. They collect data (whether or not a nest is active & # young produced) which we use to calculate the productivity rate. Ospreys need a productivity rate of at least .8 young/nest to sustain the population. In the past 5+ years they have had more than double this rate. The population has grown by 21% in the past 3 years. Last year there were 485 nesting pairs in New Jersey. This year we expect there to be even more.

 An osprey nestlings lies low in the nest. Young ospreys rely on their plumage for protection from avian predators like great horned owls.

I hope to post more photos as I survey more areas throughout New Jersey to share my experiences while working to monitor and protect ospreys. Stay tuned for more photos and posts!

• LEARN MORE

 

Tis the season!

I apologize for the infrequent posts to the blog. I've been very busy on the home front (my first child, Kaitlin, was born on April 6th) and at work (just relaunched the new website for Conserve Wildlife Foundation of NJ and blog and have started a new project working to protect terrapins in NJ).

Ospreys are currently incubating. Hatching occurs in late May-early June. High winds have been reported of having negative effects on nests along the Maurice River. 70mph gusts blew eggs out of nests. We will have to wait and see if this is reflected in the results from data collected during ground surveys in late June/early July. Otherwise, weather has been very good. Warm temperatures and normal precipitation are optimal for successful nesting by ospreys.
Otherwise, in mid-April, we installed six platforms on utility poles at Fort Monmouth in Oceanport, New Jersey. Platforms were 4 ft. square and were attached to 35 ft. utility poles. There are already three pairs of ospreys that nest on utility poles at Fort Monmouth. While we were installing the first platform, as soon as it was up, a male osprey briefly perched on the platform (see photo below)!!!

Happening Now: Spring Migration!

An adult Osprey carries its catch. Photo by Steve Byland.

In early March adult ospreys are beginning their migration to their summer breeding grounds. In the Mid-Atlantic region past band recovery data has shown that 66% of banded nestlings (older than 3 years) returned to their breeding grounds in March as compared to 91% in April (Poole & Agler 1987). Osprey nestlings that were banded last year will remain on their breeding grounds until next summer. This year ospreys that were banded in 2008 will return to the the areas where they originated. In New Jersey, 448 young were produced in 2008. We can expect that less than half will have survived to return to breed in New Jersey. Studies have shown that osprey young that hatched earlier in the breeding season have a better chance of returning to breed. Early hatching dates had a 10.5% recovery rate (306 banded v. 32 recovered on breeding grounds) while late hatching dates had a 3.5% recovery rate (200 banded v. 7 recovered on breeding grounds)(Poole 1989). Not very good statistics, but these numbers are expected for most predators, especially birds of prey.

Osprey pair at a nest site in New Jersey. Photo by Ken Connelly.

Young adults (two year old ospreys) migrate slower than older individuals. Most do not breed their first season back where they originated. So, they can migrate more slowly or leave late in the breeding season. This first year many young adults return and "house-keep" or build nests but don't reproduce. This may help them establish pair bonds that will be strengthened the following year.

Ospreys follow the same migration routes as they do in fall. Ospreys are generally known to follow direct routes and travel in stages. From Northern South America (where large numbers of ospreys overwinter) many will fly north in Hispaniola and Cuba to the Florida panhandle north along the coast until they reach their breeding grounds.

References

Poole, A.F. 1989. OSPREYS: A natural and unnatural history. Cambridge University Press. New York, NY. Pg. 63. 

Poole, A.F. & Agler B. 1987. Recoveries of Osprey banded in the United States, 1914 - 1984. Journal of Wildlife Management, 51, 148-55.

Cold Weather Ices Over Installations

This winter has been cold. Bone-chilling cold. Arctic winds have blanketed our area for some time now. They have drastically reduced surface water temperatures to the point where small bays, creeks, and ditches are frozen over. These cold temperatures have also delayed any osprey platform work (repairs and installations) until March unless temperatures rise for an extended period of time.

I have three platforms that are built and need to be installed. One in Lavallette, Little Egg Harbor, and Fortescue.

Several more platforms need repairs. Two need repairs on the Mullica River. One in Somers Point, and a few more.

Currently plans are being made to construct several more (six) osprey platforms in early February (weather permitting) at my house in New Gretna. If you are interested in helping out with repairs or installations, please let me know.

-Ben

609.628.2103

ben.wurst@conservewildlifenj.org