Grey seal males: energetic and behavioural links between size and sexual success

Balancing foraging and reproduction in the male harbour seal, an aquatically mating pinniped

“…Similar rates have been measured in other male pinnipeds that fast during the breeding season (Anderson & Fedak 1985;Boyd & Duck 1991). Thus, our findings indicate that males generally cease or substantially reduce feeding during shallow diving bouts.…”

“…Among species in which males haul out throughout the duration of the breeding season and mate terrestrially, it is possible to investigate links between body size, reproductive energetic effort, activity patterns and reproductive success through direct observation and serial reweighings of marked individuals (e.g. Boness 1984;Anderson & Fedak 1985;Deutsch et al 1990;Boyd & Duck 1991;Tinker et al 1995).…”

Proximate factors associated with high levels of extraconsort fertilization in polygynous grey seals

“…In both studies, consort males were not responsible for siring as many pups of focal females as was expected based on their behavioural status (cf. Anderson et al 1975;Boness & James 1979;Anderson & Fedak 1985). The similarly high levels of ECFs at both colonies suggest that the level of polygyny in this species based on behavioural measures of copulations or attendance patterns are probably overestimates.…”

“…The similarity in levels of ECF between Sable Island and North Rona, which differ substantially in topography and colony structure, suggest that these features are relatively unimportant within the range of variation seen. Females are less clustered at Sable Island and a single male has fewer females to defend access to at any point in time (Boness & James 1979;Anderson & Fedak 1985;this study). However, considerably more transient males roam throughout the colony at Sable Island compared with North Rona.…”

“…We used the maps to classify males similarly to earlier studies of grey seals (Boness & James 1979;Anderson & Fedak 1985), which showed that some males take up positions and defend females while others move frequently and seek mating opportunities when females might not be defended. Using a frequency distribution of male residency in a given location, Boness (1979) showed that a large number of males stayed less than 2 days, while other males stayed from 4 to 30 days, with most remaining in an area for 16-26 days.…”