New study following the movements of 50 ring-necked ducks shows that many are on the nest
Many of the ring-necked ducks in a groundbreaking Delta Waterfowl study have reached their breeding grounds and have likely begun nesting, the organization reported June 12.
A map on Delta's website shows where 15 marked ringnecks have settled. The earliest, a bird dubbed TWP, was nesting April 18. Another hen, Arden, was the latest to start nesting, on May 26.
Most of the 50 marked ringnecks that migrated from wintering sites in Florida, Georgia and South Carolina moved to the western half of their breeding range to nest, Delta said. Three died during migration or at nesting sites. A Cree Nation man in Manitoba shot one. Ducks named Angel and JHP apparently died relatively early in spring but were at their final locations long enough to have started nests.
Nesting females are certainly most vulnerable to predation at the nest, Delta said in a press release. The transmitters for the two dead hens are still giving locations, but the temperature of the transmitter is low and matches the background environmental temperature — a sure sign the bird is dead.
Four ducks are still transmitting locations but remain on the move. They will be classified as non-breeders if they don't settle soon.
We have long suspected that some females don't initiate nests, the release said. The transmitters might increase the probability of a non-breeding event, as has been proven in other duck studies. The most interesting traveler is HMP, a duck that went to Great Slave Lake in the Northwest Territories before heading south 540 miles to her current location in western Saskatchewan.
Delta said 21 ringnecks were implanted with new Ornitela transmitters, which the group believes are still functioning. Those devices collect location data more frequently and accurately than the old-school Geotrak transmitters, which were used exclusively in the 2018 portion of the study and represent half the 2019 transmitters.
The downside of Ornitela transmitters for these remote, northern-nesting ducks is that they send the location data via cell phone signals, so there must be a cell tower near the bird when the transmitter turns on and tries to send location data, Delta said. If there is no cell tower, then the transmitter stores the location data until the next timed transmission event. So, the map shows a lot of migration tracks, but most end where high human density civilization ends, as does the abundance of cell towers. One surprise is ringneck No. 182657, which migrated to northern Ontario and stopped near one of the few cell towers in that fairly remote area.
Delta said researchers are optimistic the Ornitela-fitted females will survive summer and then transmit their stored locations when they return south in early fall.
We hope to get a goldmine of location data that shows the last parts of the spring migration, nesting sites, the sites where birds underwent their annual wing molts (when they were flightless for three to four weeks) and the initial fall migration tracks, the release said. Of course, the ducks have to survive, and the transmitters have to continue to function. This is the first use of these advanced transmitters for a northern-nesting duck, so we have our fingers crossed.
Beginning Nov. 28, 2018, Delta Waterfowl and its research partners inserted transmitters in 61 ringnecks — 30 originating in South Carolina and 31 more in southern Georgia and northern Florida. This season's study, the second in a two-year effort, includes two drakes. In November 2017, Delta implanted radios in 15 ringneck hens in the same area of Georgia and Florida. The transmitters let Dr. Mark McConnell and graduate assistant Tori Mezebish, of the University of Georgia, track movements of the hens at their wintering grounds and allowed them to follow the ducks' spring migration to Canadian breeding grounds before the transmitter batteries expired.
The study, conducted cooperatively by Delta and the University of Georgia, is exciting for several reasons. Ringnecks have been studied far less than any of the most harvested duck species. Further, they are expanding in numbers and range, so the study marks one of the first times researchers can study a duck species on the upswing. In addition, this is the first time researchers have implanted radio transmitters in ringnecks to study their movements. Banding data for the species is lacking, so biologists know relatively little about the birds' migration routes or breeding destinations.