Elephant seal foraging dives do indeed track prey distribution, but temperature influences the distribution of prey: Reply to Boersch-Supan et al. (2012)

Abstract

ABSTRACT: McIntyre et al. (2011a; Mar Ecol Prog Ser 441:257−272) illustrated a number of rela-tionships between environmental variables and the dive behaviour of satellite-tracked southernelephant seals Mirounga leonina . One of these associations was that seals tended to increase theirdive depths and spend less time at targeted dive depths when swimming in warmer waters.Boersch-Supan et al.’s (2012; Mar Ecol Prog Ser 461:293−298) comment on this study suggests thatthe link described between dive depths and in situ temperature is actually a link between divedepths and prey distribution. We do not dispute this assertion, having discussed this likelihood inMcIntyre et al. (2011a). Boersch-Supan et al. (2012) further provide a number of criticisms, basedpartly on their observations of potential prey distributions within a comparatively small geo-graphic area. We argue that their results are not directly comparable to those presented inMcIntyre et al. (2011a) given the limited spatial overlap of the study areas and sparse, small-scaledataset presented. We further provide replies to technical comments by Boersch-Supan et al.(2012) pertaining to our data analyses.KEY WORDS: Southern elephant seals · Foraging ecology · Climate change · Marion Island · Bio-logging