호주
The mating system of the Weddell seal, Leptonychotes weddelli
Metadata record for data from ASAC Project 2184 See the link below for public details on this project. The objectives of this project were: To characterise the mating system of the Weddell seal by: 1) acoustically tracking males under the ice during the breeding season, 2) measuring changes in health and condition of individual males over the breeding season, 3) determining whether vocalisations are used as advertisements of individual quality to attract females, and/or in male-male competition, 4) develop and use a combination of microsatellite loci tests to assign paternity to newborn pups, and then use these results to determine whether the variance in male mating success is related to territory size, tenure and/or individual characteristics. A large number of collected data files are available for download. Many files are in an unknown format, but will open with a standard text editor. See below for summaries of the two seasons of fieldwork. 1997/1998 Season: In November/December 1997, we conducted a pilot study at the Turtle Rock colony (77.727S, 166.85E) in McMurdo Sound. All of the techniques outlined in the proposal were successfully trialled. Acoustic pingers were attached to seven males and five females for a total deployment of 104 seal days and mass and morphometrics obtained for each animal. Preliminary analysis of male movements indicate that males held adjacent yet non-overlapping territories on the southern side of Turtle Rock, along a major ice crack and where the congregation of females was highest. Both the size and shape of the males territories, and the evidence from the vocalisation data show that we captured the dominant males at the site. Both males and females were immobilised using Ketamine/Diazepam with no loss of an animal, nor signs of respiratory depression. Vocalisations were recorded from all territory holding males, and both behavioural and vocal responses of both male and female seals to familiar and unfamiliar calls were observed. We bleach marked all animals to which we attached pingers and these markings were visible on our under-ice video - with which we also recorded behavioural responses to both animals and our under-ice speaker during playback experiments. We conducted a daily census of all animals at Turtle Rock and above-ice movements were recorded. Skin samples were taken from 24/25 males seen at the site and 43/45 mother-pup pairs (One male was only seen on a single occasion at the colony, though sighted elsewhere, and two females disappeared shortly after our arrival at the colony). Significant findings Dominant males hold under-ice territories which are adjacent yet non-overlapping - however territory boundaries change considerably over the course of the breeding season. Males respond to playbacks of their own and others calls as do females. Females towards the end of lactation will visit each males territories. Whether to assess individual males or not is yet to be determined. 1998/1999 Season Between October 29 through December 10 1998, the behaviour of male and female weddell seals at the Turtle Rock colony (77.727S, 166.85E) were monitored both above and below the ice. This season, we switched from the seal sled method of capture and restraint (see K027 report 1997) to the use of a pole net and tripod. Seals were bagged by placing a seal hood over their head and then a 3m pole net (consisting of two, 3m long poles connected by a 2m wide, 2.5cm mesh, net , was placed over them and the poles tied tightly at both ends, leaving them constrained within the netting bag. The pole net was then hoisted under a tripod (built by Antarctica New Zealand) using a chain block suspended from the head of the tripod, and the animal weighed using electronic scales. For attachment of instruments, animals were immobilised with an intra-muscular injection of Ketamine/Diazepam at a dose rate of approximately 2.0mg/100 kg Ketamine, 0.4mg/100 kg Diazepam as was used successfully in 1997. Animals were