Food caching behavior of the Eurasian beaver in northern Europe

Peter E Busher,Frank Rosell,Alius Ulevičius,Göran Hartman,Arunas Samus,Martin Mayer

doi:10.2981/wlb.00734

Abstract

Food storage (caching, hoarding), which is observed in many species of animals, increases food availability during times of food insecurity. Both species of beaver (Eurasian beaver, Castor fiber, and the North American beaver, C. canadensis) living at northern latitudes where food may be scarce during winter are larder‐hoarders, constructing a food cache of branches of woody species during autumn. We studied the food caching behavior of the Eurasian beaver in three northern European countries (Sweden, Norway, Lithuania) to provide additional insight into this important behavior. Thirty‐seven of forty‐seven (79%) active family groups had food caches by mid‐November and 41 of 47 (87%) had caches by December. Water depth of caches ranged from 1 to 2.3 m and depths at caches in Sweden were significantly deeper than in either Norway or Lithuania. Construction of caches began as early as late September (week 39/40) in Sweden and Lithuania and by mid‐October (week 42) in Norway. We observed plasticity in timing of cache initiation but the majority of active sites in all areas had food caches by the beginning of November (week 45). Declining air temperature and mean minimum temperatures of 0°C or below were associated with cache initiation. Caches in Lithuania were larger than in Sweden and Norway, which may be associated with colder winter temperatures. We did not find any relationship between family size or length of territory occupancy and cache size at our Norway sites where population demographics were available. Our results are generally consistent with other studies of food caching behavior in both species and suggest general similarities as well as behavioral plasticity in this important evolutionary strategy.

Highlights

Storing food is an evolutionary strategy that allows many species of animals to overcome times of food scarcity (Andersson and Krebs 1978, Smith and Reichman 1984)
The two extant species of beavers, the Eurasian beaver, Castor fiber, and the North American beaver, C. canadensis, are found across a large latitudinal range in the Holarctic biogeographical region occurring in most types of wetland habitats including large and small lakes, ponds, large and small rivers, streams, and in human modified systems such as agricultural drainage and irrigation ditches and fish ponds
We examined water depth at food caches, initial cache size and date, temporal growth of caches and the potential relationship between cache initiation and cache size and ambient temperature

Summary

Introduction

Storing food is an evolutionary strategy that allows many species of animals to overcome times of food scarcity (Andersson and Krebs 1978, Smith and Reichman 1984). The ability to collect and store food at one time and use it at another time is an important evolutionary adaptation and allows species to successfully cope with changing food supply and energy demands. The food cache along with fat storage (Aleksiuk 1970, Smith and Jenkins 1997) reduced activity (Aleksiuk and Cowan 1969, Potvin and Bovet 1975, Lancia et al 1982), construction behaviors and social behaviors (Semyonoff 1953, Stephenson 1969, Buech et al 1989) allows the beaver family to meet metabolic demands and overcome reduced food availability during the winter

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