Intra-seasonal variation in zooplankton availability, chick diet and breeding performance of a high Arctic planktivorous seabird

Dariusz Jakubas,Katarzyna Błachowiak-Samołyk,Dorota Kidawa,Lech Stempniewicz,Rafal Boehnke,Katarzyna Wojczulanis-Jakubas

doi:10.1007/s00300-015-1880-z

Dariusz Jakubas, Katarzyna Błachowiak-Samołyk + Show 4 more

Open Access

https://doi.org/10.1007/s00300-015-1880-z

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Abstract

Different phenological responses to climate changes by species representing preys and predators may lead to mismatch between functionally dependent components of an ecosystem, with important effects on its structure and functioning. Here, we investigate within-season variation in zooplankton availability, chick diet composition and breeding performance of a small planktivorous seabird, the little auk (Alle alle) in two large colonies in Hornsund and Magdalenefjorden, Spitsbergen, differing in synchrony of breeding (11-day vs. 22-day hatching period, respectively). Assuming similar zooplankton phenology and existing differences in duration of the little auk breeding period, we expected lower availability of the preferred food in the less synchronized colony in Magdalenefjorden and in consequence a negative effect on nestling body mass and survival. We found that in both colonies Calanus glacialis (copepodite stage CV) was the most important prey item in the chick diet making up 68–87 % of the biomass and energy of all prey items. The only exception was the end of the chick-rearing period in Magdalenefjorden, when contribution of this prey item was significantly lower (24–26 %). Thus, late breeders in Magdalenefjorden were apparently mismatched regarding C. glacialis CV availability. However, the hatching date did not affect birds fitness (reproductive output and chick pre-fledging mass) significantly. Results of our study indicate that little auks breeding on Spitsbergen can respond to a wide range of environmental conditions and prey availabilities through the plasticity of their foraging behaviour, which may help them to maintain their optimum fitness level in changing and unpredictable environments.

Highlights

Inter- and intra-seasonal changes in environmental conditions and food availability often affect foraging behaviour and diet of animals including numerous bird species (e.g. Morrison et al 1990; Watanuki et al 1993; Charrassin et al 1998; Jakubas and Manikowska 2011)
We found that in both colonies Calanus glacialis was the most important prey item in the chick diet making up 68–87 % of the biomass and energy of all prey items
Results of our study indicate that little auks breeding on Spitsbergen can & Dariusz Jakubas biodj@univ.gda.pl

Summary

Introduction

Inter- and intra-seasonal changes in environmental conditions and food availability often affect foraging behaviour and diet of animals including numerous bird species (e.g. Morrison et al 1990; Watanuki et al 1993; Charrassin et al 1998; Jakubas and Manikowska 2011). Interpretation of changes in diet may differ between ecological groups. It may indicate prey switching, i.e. increased predator selection for a particular prey species when it is abundant and decreased selection when it is scarce Recognizing changes in diet of specialized predator within the breeding period may indicate changes in foraging conditions, especially in the case of predators breeding in seasonal environments. They schedule their most energydemanding life-history events, such as reproduction to coincide with the peak of abundance of the preferred food. Climate changes shift annual cycles of multiple organisms (Parmesan and Yohe 2003; Root et al 2003) and predators may respond differently

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