Tag: osprey

A healthy population

Posted on by Ben Wurst
Osprey numbers continue to rise

by Ben Wurst, Habitat Program Manager

Three osprey nestlings at a nest near Osbourne Island. © Eric Sambol

Ospreys are currently listed as a threatened species in New Jersey. They were first listed as endangered in 1974 after the state population declined to only 50 pairs, from over 500 prior to 1950. Ospreys have made a remarkable recovery in New Jersey thanks to biologists with the Endangered and Nongame Species Program (ENSP) and many volunteers. Surveys that help monitor the population were conducted in late June and early July.

Volunteers and biologists surveyed all major nesting colonies from Sandy Hook south along the Atlantic Coast to Cape May and west to Salem County. Ospreys almost exclusively nest on man-made structures including platforms designed specifically for them, cell towers, duck blinds, channel markers, and boat lifts. Surveyors visited these nest structures to observe whether or not they were occupied. If they’re occupied, then the number of young were recorded and the young were banded for future tracking with a USGS bird band. Preliminary results show that productivity rates are up for all nesting colonies except one (Sedge Island WMA). Since ospreys are predators, they are at the top of the food chain. They are considered to be an indicator species, or a species that is sensitive to changes in environmental conditions and can serve as an indicator of an unhealthy marine ecosystem. Basically, a healthy osprey population means a healthy marine ecosystem.

The climate during this summer has been the complete opposite as last year. It was hot, dry, and calm, with only a few severe storms with high winds that caused some nests to fail. Otherwise, fish stocks are plentiful, especially menhaden. This year many out-of-state commercial fishing boats have started fishing for bunker off New Jersey waters. This is mostly due to declines in herring stocks in New England and the high demand for bait for use in lobster pots. State legislators have introduced a bill that would limit boats from catching bunker for use as bait. Read more here and this press release from the Recreational Fishing Alliance.

Full results from this years survey will be published soon in our annual newsletter. Here is last year’s newsletter.

Lost Connection

Posted on by Ben Wurst
To the internet, not wildlife!

By Ben Wurst, Habitat Program Manager

The office where I work, inside Tuckahoe Wildlife Management Area in northern Cape May County, recently lost its connection to the world wide interweb. The office is home to the NJ Division of Fish and Wildlife staff and three CWF employees. Since the demise of our connection to the world wide interweb the office has been ghostly quiet. Some have chosen to work at home, use some vacation time, or get some field work done. I just wrapped up my primary field season surveying osprey nests along the Atlantic Coast of NJ so I chose to be constructive, literally. I started constructing some artificial nesting platforms for ospreys. Normally I do this in the winter when field work is very limited, but finishing these now will give me a chance to install them this fall. Late summer and fall are the best times to install platforms. The water and air are warm and the winds are calm, so boots and bulky clothes aren’t required. So, I’m glad the internet is down because it gave me a reason to construct these platforms earlier than usual.

An osprey platform sits while I work on the finishing touches. This image was shot using a technique referred to as HDR. © Ben Wurst

Two platforms will be going up in Lavallette, one near Tuckerton, and the other has yet to be determined (possibly Sea Isle). Stay tuned for more updates and photos!


Photo from the Field

Posted on by Ben Wurst
An osprey nestling lays low in a nest

By Ben Wurst, Habitat Program Manager

The iris is the thin colored part of an eye that is responsible for controlling the size of the pupil and the amount of light that enters the pupil. As a hatching the iris of an osprey is blood red in color. As a nestling (pictured below) they turn to an amber or orange color. The eye color and plumage of juveniles help distinguish them from adults, which have a yellow iris. Juvenile ospreys also have “buff” or tan feather tips on their contour (body) feathers. This helps camouflage them before they can fly and it also helps distinguish them from adults, who have dark brown body feathers.

An osprey nestling relies on the cryptic coloration of its plumage to protect it from avian predators. © Ben Wurst

To see more photos of ospreys and their young, click here. Check out the slideshow at the top of the page.

Ospreys Love Garbage…but the mix can be deadly

Posted on by larissasmith

By Larissa Smith, Biologist & Volunteer Manager

Rope and fishing line found in an osprey nest © Matt Tribulski

Ospreys love to bring garbage back to their nests. While out checking on nests I’ve found everything from rope, fishing line, flip flops, plastic bags, a Frisbee, hats and even a plastic crab in nests.  The problem is that every year while volunteers and staff are checking on nests at least one chick is found entangled in this garbage. Fishing line gets caught around their feet and legs and a plastic bag can entangle a chick.  If no one went out to check on these nests most of these chicks wouldn’t make it.  It’s not only the chicks that suffer from the garbage we throw out. Adult ospreys have been found dead and hanging from fishing line.  Ospreys and other species whose diet consists of mostly fish are particularly vulnerable to injury and death from fishing line and hooks.  During a visit to an NJ eagle nest a chick was found with a fishing hook embedded in its mouth.  I have also found horseshoe crabs and terrapins entangled in fishing line and these are just a few examples of  how garbage effects wildlife.

Plastic bag in osprey nest © Matt Tribulski
There are some simple steps that we can all take to keep trash out of the environment.
  • Pick up and dispose of any fishing line or hooks you use or find.
  • Use reusable bags instead of plastic whenever possible and encourage others to do the same.

Thank you!

Assessing the Population

Posted on by Ben Wurst
Keeping tabs on the osprey population in New Jersey

By Ben Wurst, Habitat Program Manager

An adult osprey flies over me while I band its young. © Ben Wurst

Over the past few weeks volunteers and biologists have been performing ground surveys to help determine the health of the osprey population in New Jersey. The surveys are part of the NJ Division of Fish and Wildlife, Endangered and Nongame Species Program, Osprey Management Project. Ospreys are listed as a threatened species in New Jersey. They were originally listed as endangered in 1974 after only 50 nesting pairs were found in 1973. By 1986, their status was upgraded to threatened after their population rebounded to 100 nesting pairs. Today there are over 450 pairs of ospreys that we help to monitor in New Jersey.

Climbing a nest on Great Bay. © Bill Steiner

Ospreys are highly dependent upon humans to provide artificial nesting structures for them and they are highly susceptible to many different heavy metals and persistent organic pollutants like DDT, DDE, PCBs and more recently brominated fire retardants (PBDE) that bio-accumulate in the food chain.

Surveys are performed each year during summer when osprey nestlings are old enough to band (3-6 weeks old) but not old enough to fly. They cover all major nesting areas including, the Delaware Bay, Raritan Bay south to Cape May, and inland.  During ground surveys nestlings are banded with USGS aluminum leg bands for future tracking. I survey areas from Great Bay in Little Egg Harbor north to Fort Monmouth in Oceanport and Mantoloking along the Atlantic Coast.

A five week old osprey nestling. © Ben Wurst

The data we collect (whether or not a nest is active and the # of young produced) is used 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% from 2006 to 2009. Last year there were 485 nesting pairs in New Jersey. This year we expect there to be even more. Last years results are summarized in the 2009 Newsletter.

Ben Wurst and Jeff Sloane from US Fish and Wildlife stand in front of a platform that was repaired along the Mullica River this year. © Ben Wurst

Last year was a record-breaking year. Before the effects of DDT, habitat loss and persecution decimated the population in the mid-1900’s there were over 500 nesting pairs. Since the mid-1970’s, when the project began the population has slowly risen to its current level. Each year more platforms are damaged by harsh winter weather and the extremes of being located in saltmarshes. Work is continual and never ending. Repairs to existing platforms occur during the “off” season or non-breeding season from late August to the end of March. New platforms (built with stainless and galvanized hardware, that are meant to last) are placed in areas where suitable habitat exists where little to no available nest sites occur. It is our goal to help the population recover to historic numbers.

Preliminary results show that some areas fared very well this year. The colony from Little Egg Harbor to Atlantic City had 25 active nests that produced 57 young. Last year, 36 nests produced 55 young. The climate has been optimal for ospreys, except for the occasional thunderstorm with high winds. Temperatures have been above normal and precipitation has been below normal. Full results from the season will be available this fall once the survey results are collected and summarized.

Our work would not be possible without the support of our members and volunteers. Thank you!

Photo from the Field

Posted on by Ben Wurst
Monitoring Ospreys in New Jersey

By Ben Wurst, Habitat Program Manager

On June 29th I visited Fort Monmouth to survey the nesting platforms there. Four structures were occupied including this platform that was placed along a tributary of the Shrewsbury River, an area in need of more nesting structures for ospreys. A total of 8 young were produced there this year. The young were banded with a federal USGS bird band for future tracking.

The view from a man lift that provides easy access to an osprey nesting platform at Fort Monmouth. © Ben Wurst

Ospreys in New Jersey

Posted on by Ben Wurst
Eggs will be hatching soon!

By Ben Wurst, Habitat Program Manager

Ospreys normally lay between 2-3 eggs in a clutch. They are light tan with dark brown blotches. © Ben Wurst

Osprey pairs are very busy this month. Females are hunkered down in nests while incubating their eggs. They must keep their eggs at a temperature of around 99 degrees Fahrenheit. They must maintain this temperature for over 32 days and up to 43 days! Warm air temperature and normal precipitation are crucial during incubation. If there are periods of extended rain and cool temperatures, then the success rate at raising young decreases.

Eggs are incubated immediately after they are laid. This is referred to as asynchrony. This ensures that during times of low prey availability at least one nestling will survive to fledge or leave the nest. Disturbance is critical to incubating females now. If they must leave the nest, then the eggs are very vulnerable to the suns radiation, cool air temperatures, and predators. Females do 70% of the incubation duties.

While females are sitting there, incubating those eggs, males are mostly on the wing or perched near the nest. They provide almost all of the food to the female. They can fly a few miles from the nest, or only a few hundred feet to find prey (live fish). This is why ospreys nest near water, their source of food. The males ability to provide food to the female is also crucial to the success of the pair at raising young.

An osprey feeds its young on a nesting platform. © David Carr

The young hatch (in the order that they were laid) and are born semi-altricial, or blind, feathered, and completely helpless. They are totally dependent on their parents to keep them warm and to provide them with food. They need very close parental care during the first week of life. After the first week the nestlings begin to more around more and begin exploring the surroundings in their nest. At three weeks of age (pictured at right) the nestlings can easily walk around the nest and often raise their heads to look around. Their contour (body) feathers and flight feathers begin to emerge from their protective sheaths during this time. The coloration of their feathers (dark brown with a buff feather tip) give them remarkable camouflage in the nest. Their coloration is very close to the nesting material ospreys use which consists of sticks, seaweed, marsh grasses, and human garbage like plastic bags, fishing line, and other trash.

Here you can see the large amount of ribbon in the nest and around the leg of an osprey chick. © Bill Steiner

I find a lot of ribbon from Mylar balloons every year. Some nestlings become entangled in the ribbon. If I do not get to the nest in time and remove the ribbon, then some may lose a limb or even die. It is not clear why adult ospreys choose to use fishing line and ribbon as nesting material. It may be because it is fairly common (unfortunately) in marine and estuarine ecosystems.

Keep an eye for hatching to begin two weeks from now. Females will not be sitting as much and they will be more aware of those eggs that are hatching beneath them. In late June and early July, volunteers throughout coastal areas will perform surveys by boat to determine the health of the population. I’ll post more updates soon on this in the coming weeks.

In the meantime, if you’d like to help, participate in coastal clean-ups or if you’re out for a walk or hike, bring a small trash bag and pick up some trash!