Seabird foraging behaviour indicates prey type

Abstract

To investigate how a generalist marine predator modifies its foraging behaviour by prey type, we attached time-depth-temperature recorders to chick-rearing thick-billed murres (n = 204) at Coats Island, Nunavut, Canada from 1999 to 2007. Predators varied their behavior along 3 major 'axes': foraging effort, prey depth and prey lifestyle (benthic/pelagic). Dive behaviours for different prey -fish doctor, squid, sandlance, amphipods, snakeblenny, daubed shanny, sandlance and Arctic shanny -were discriminated from one another in a discriminant analysis of dive variables and these prey were therefore considered 'specialist' prey items. Specifically, amphipods were captured during V-shaped dives near the colony with a slow bird descent rate, squid were captured during deep V-shaped dives in cold water and fish doctor were captured during a long series of U-shaped dives in relatively warm water far from the colony. Arctic shanny and snakeblenny tended to be taken at moderate distances from the colony, with snakeblenny taken at deeper depths. Daubed shanny captures showed a bimodal distribution, with some taken at shallow depths far from the colony and others at deep depths close to the colony. Dive behaviours for Arctic cod, capelin and sculpin overlapped both with each other and the behaviours for specialist prey items and, therefore, were classified as 'generalist' prey items. In general, V-shaped dives preceded deliveries of pelagic prey items and U-shaped dives preceded deliveries of benthic prey items. Our results strongly suggest that generalist marine predators use stereotypic behaviour to forage for prey items, based on previous knowledge about what locations/strategies maximized intake for a given prey type.

Oxygen stores and foraging behavior of two sympatric, planktivorous alcids

“…F: female; M: male. Individual dive depths and durations for murrelets and auklets are available in Tables S1 and S2, 22.4 ± 4.0 8.9 ± 3.1 87.4 ± 9.9 36.0 ± 13.7 recapture rates and low mass loss, easy-to-obtain measures of device effects on the adults, such as mass loss, corticosterone concentration and device retrieval rates, may mask subtle attributes, including time spent feeding, dive behavior and at-sea activity, because of compensation by the mate or because the costs are passed on to the chick (Paredes et al 2005, Elliott et al 2007, 2008a, Takahashi et al 2008. Consequently, devices as low as 1% of body mass may well be impacting measurements of the very parameters they are trying to measure (Table 1), although it is sometimes unclear whether the effects are due to the devices or to handling.…”

“…Sources are shown in Table S3 the maximum distance traveled from the colony was likely much less (Elliott et al 2009a, Thaxter et al 2009). The differences in foraging behavior between auklets and murrelets either represents different foraging tactics for capturing the same prey or differences in prey type, as foraging behavior indicates prey type in other alcids (Elliott et al 2008a). The dive depths and durations of auklets and murrelets were comparable to those of 150 g planktivorous dovekies Alle alle, while dive shape was comparable between dovekies and murrelets (Harding et al 2009, Table 4).…”

Trade-offs in prey quality and quantity revealed through the behavioral compensation of breeding seabirds

“…Compensation can take a variety of forms, such as a bimodal foraging strategy (Chaurand & Weimerskirch 1994, Weimerskirch et al 2003, Welcker et al 2009a), individual differences in foraging habitats (Elliott et al 2008b(Elliott et al , 2009, or simply an increase in trip duration and/or foraging distance (Suryan et al 2002, Burke & Montevecchi 2009, Pichegru et al 2010. In some cases adults expend more energy to increase feeding rates and/or take higher quality prey (Jodice et al 2006, Deagle et al 2008, Welcker et al 2009b; but see Welcker et al 2010).…”

Convergent Foraging Tactics of Marine Predators with Different Feeding Strategies across Heterogeneous Ocean Environments

“…Linking movement patterns to habitat use remains, however, a challenging task. Detailed records of prey abundance and distribution and accurate indices of feeding are difficult to obtain for the majority of species and although visual assessment of prey capture is possible for some species (Seminoff et al, 2006;Elliott et al, 2008), in most cases, indirect parameters have been used as a proxy (e.g., gastric or visceral temperature changes, mouth/beak opening or head/jaw movement, accelerometer signatures; Sepulveda et al, 2004;Gleiss et al, 2011aGleiss et al, , 2013Nakamura et al, 2011Nakamura et al, , 2015Carroll et al, 2014;Nakamura and Sato, 2014). For efficient foraging by predators, patterns of habitat use are assumed to reflect the distribution, density and quality of prey resources (Stephens and Krebs, 1986;Austin et al, 2006;Carroll et al, 2017).…”