Migration - 2007 Introduction:
Status of our migration studies. If you would like to be included in an email list to receive a notice each time maps are updated, send me an e-mail: rbierreg@email.uncc.edu
Adult females migrate about a month before males, and adults of both sexes are very faithful to their chosen wintering grounds. Because young experience a very high mortality rate and satellite transmitters are very expensive, only a handful of first-year Ospreys had been tagged prior to 2004, and thus their migration is poorly understood. When do they go south? How do they find a reliable wintering area? Do they spend time exploring or chose the first good spot they find? We know from traditional banding studies that they stay on the wintering grounds for at least a year and a half. Do they all return in their second year? Do they go all the way home on their first return? With five young tagged in 2006 and five to be tagged in 2007, we will have tagged 15 fledgling Ospreys, which more than doubles the number of first-year birds that have been tagged anywhere else, as far as I know. By "cherry picking" young from old, established breeding pairs, and trapping young that have already been flying for a couple of weeks, we have significantly beaten the odds--only one of the five young tagged prior to this year did not make it to the Caribbean. The Class of '04: On his migration south in the fall of 2005, our only tagged adult Bluebeard was shot (almost certainly) just a couple of hundred miles north of his wintering grounds. That left only Jaws, a fledgling tagged in 2004, as a candidate to return to Martha's Vineyard in the spring of 2006, and his safety was in question as the year began. Our last signals from him were in December of 2005, and those were intermittent. We suspected a malfunctioning transmitter, given that he had been in what appeared to be Osprey heaven down in Colombia, with lots of fish and no one around that shoots Ospreys. Lo and behold, in May someone spotted an Osprey flying through eastern NC (when Jaws should have been moving back for his first trip home). In late May his transmitter turned on for a couple of days as he arrived back in his natal area. There's some sort of problem with his solar panel, so we only get very sporadic messages from him, but he's out there. Since then, he has returned to the Gulf of Venezuela to spend the winter of 2006-07 and returned again to Martha's Vineyard in April 2007. The Class of '05: Homer spent a year and a half down south in Venezuela before heading home. Homer made it back to the Vineyard, while Conanicus started migrating but never made it to the north coast of Cuba, probably another victim of shooting. The Class of '06: We didn't have much luck with the 5 birds tagged in the summer of '06. Of the 2006 birds, only Della, tagged in the Delaware Seashore State Park, is left. She is down in the middle of the Brazilian Amazon and should return in the spring of '08. But this is pretty much what we expect--mortality in first year birds is probably between 80 and 90% over their first migration cycle. WHO'S WHO? (Click on the bird's name to get to its series of maps.) Jaws - Tagged in '04, this young male is back on the Vineyard with a mal-functioning transmitter. With luck, we may be able to retrap him next year and get the bad transmitter off him. We haven't had any signals from his radio (nor any sightings) since May 6th. We hope he'll show up at a nest next year, where we may be able to trap him and get the radio off his back. Homer - After turning a 3,500-mile migration into a 5,200-mile odyssey (he was named for the pond near his nest, not in anticipation of his extended travels!), Homer finally (March '06) settled down at a reservoir to his liking and in April was making occasional trips some 30 miles to a mountain valley west of his reservoir. He has shown a predilection to mountain rivers throughout his migration. He arrived back on Martha's Vineyard on 20 May, 2007, a couple of weeks after his second "hatchday". Conanicus - Our Rhode Island youngster, tagged as a recent fledgling in '05, frequented the Zapata swamps in southwestern Cuba for a year and a half. He began his '07 migration on the 29th of April and sadly ended his trip at a fish farm. NEW BIRDS for 2007 This year's trapping began on 25 July at the SPI-Pharma facility next door to the Cape Henlopen State Park (CHSP). CHSP and the Friends of Cape Henlopen are sponsors of the two Delaware transmitters this year. (As above, click on the bird's name to go to its migration maps.) Claws - I grabbed this young male off his nest atop an 80' water tank at the PSI Pharma facility that makes milk of magnesia from water taken from below CHSP. The nest is rigged with a camera that feeds to a TV monitor at the State Park Nature Center a half mile or so away. His sibling, hatched a full week after Claws, was not ready to fly. As it turned out, Claws could indeed fly, he just didn't know it yet.
Patience - This young female was tagged in the Delaware Seashore State Park, south of Dewey Beach, just a mile or so north of the Indian River Inlet. The nest is the neighbor of the nest where we tagged Della in '06.
On the 26th I flew to Martha's Vineyard for the final leg of the trapping trip. Luke - Early on the 27th, Dick Jennings and I set up our noose carpet at the Mink Meadows nest on the Vineyard's north shore. This has been one of the most productive nests since I re-started the Osprey census in 1998 and this year fledged two young. When we set up at 0630, there was not an Osprey in sight, which made us needlessly nervous. Around 8 we had an adult show up and by 9:15 a young bird landed on the nest and was caught. We tagged this bird with a GPS transmitter. The bird is named in memory of John Luke, a great friend of my family and a devoted Ospreyphile who lived in the Mink Meadows Osprey's backyard--or is it vice-versa? Felix - On the
28th we set our noose carpet on the nest at Mass Audubon's Felix Neck Wildlife
Sanctuary. Mass Audubon has been a great supporter of the tracking work, kindly
processing all our finances, and the 60-70 Ospreys that now nest on the Vineyard
are pretty much there because of the efforts of long-time Sanctuary Director Gus
Ben David. Gus, who retired a couple of years ago, and his Osprey crew are
responsible for most of the 115 nest poles on the Island, so it was an obvious
place to tag a bird, and the name was similarly easy to come up with. We were
ready with "Felicity", had our bird turned out to be a female. In
fact, we're not completely sure we shouldn't have used Felicity to name this
bird. Female Ospreys, like all birds of prey, are larger than males. It's pretty
obvious when you have a small male or a really large female, but sometimes the
intermediate birds are a bit tricky to sex. Let's just say I wouldn't be
completely surprised if Felix comes back to the Vineyard in 3 or 4 years and
lays some eggs!
Trapping went fairly smoothly--no problems with
catching adults this time, and that was a good thing! The nest in Delaware,
where we caught 3 adults, was only about 12 feet off the marsh, so it was no big
deal to throw the ladder up to the nest and extract our birds. The Felix Neck
nest is about 40' high, so I have to use a ladder to go up the first 20' and
then pole spurs then next 20'. I did not want to do that for anything other than
our target youngster, so we were ready to run up to the nest and deflect any
adults that came in on a landing approach.
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