Sunday, June 29, 2008

Surveying the popuation

1 Week old osprey chick. N. Wildwood.

June 29, 2008 - It's that time of year, summer is here and the 4th of July is approaching fast. It's my busiest time of the year when I survey several different areas along the coast to monitor the osprey population. Areas that I've covered so far include, Sedge Islands (Island Beach State Park), Barnegat Bay, Little Egg Harbor, Absecon and A.C., Tuckahoe River, and Great Bay. This next week I plan on visiting nests at Cheesequake State Park, the Mullica River, and Margate/Ventnor. We have several volunteers who dedicate a lot of time and money to surveying other dense colonies and they include Sandy Hook, Stone Harbor/Avalon, Wildwood, Dividing Creek, and the Maurice River. Without the valuable data that our volunteers contribute we would not be able to accurately estimate the annual health of the population.

Right now many osprey nests contain young that differ in ages from a couple days old to almost 6 weeks, while a few are still incubating. While surveying, I collect information on each of the nest platforms and record if the nesting structure is occupied by a pair of ospreys and if they produced any young. With this data we then summarize the results and for all survey areas to determine the average productivity rate (# young produced/active-known outcome nest). A nest with a known outcome is an active nest that either has produced young (observed in the nest) or has failed (lost it's eggs or young due to many different factors; one could be weather related or the availability of food). Below is a chart of the # of active nests and productivity rate over the last 10 years in NJ.

# Active nests (bar) and productivity rate (line)
over last 10 years in NJ.
So far, this year is looking good. With more platforms available, and plenty of fish stocks, weather has only played a minor role in determining nest success. We only really had one bad storm this spring; the mid-May Nor'easter. Most ospreys weathered the storm and protected their clutch (of eggs). Luckily hatching usually occurs in late-May/early-June. From what I've seen, most young appear to be well-fed, healthy, and are growing quickly. When we get the data collected from our volunteers, then we'll be able to see just how good or bad this season was. Stay tuned!!

My view, accessing the nest platforms.

5 week old chick.

USGS leg band

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