The contribution of the vegetable material layer to the insulation capacities and water proofing of artificial Mus spicilegus mounds

Abstract

a b s t r a c tSuccessful overwintering of small mammals in temperate and cold climates requires behavioural and physiological adaptations. There are several strategies to survive food shortages and the cold. Most species of small mammals use multiple methods simultaneously but nest building and burrowing are the most widespread among them. A well-constructed, dry nest insulates animals from harsh ambient conditions. Mound-building mice build large banks in the autumn and establish a burrow system with nest chambers beneath them. These overwintering structures are built from soil and a considerable amount of plant material. Recent studies presume that the stored vegetable matter does not, or not exclusively, serve as food and indicate that the mounds might have insulating role. To investigate the function of their plant fill, we built artificial mounds with varying plant content, similar to those built by mound-building mice. We measured temperature change at three levels, at the surface, under the mound and at the nest depth, and investigated their water retaining properties. We showed that the plant fill plays a major role in their thermal insulation and waterproofing properties. Mounds reduced temperature variation of the soil and may protect the nest from absorbing precipitation during the winter.

Are there differences in the morphology of communal mounds of overwintering mound-building mice (Mus spicilegus Petényi, 1882) in Slovakia?

“…Further data from Romania (Hamar 1960), Austria (Festetics 1961, Unterholzner & Willenig 2000, Hölzl et al 2009, 2011a, Moldova (Muntyanu 1990, Simeonovska-Nikolova et al 2014, Bulgaria (Simeonovska-Nikolova et al 2014) and Hungary (Bihari 2004, 2007, Szenczi et al 2011, 2012) also confirmed previous observations on mound morphology.…”

“…A specific ecological and ethological feature of M. spicilegus is its grain-hoarding activity. In autumn, groups of several individuals build special mounds in which they store the seeds of weeds and cultural crops for the winter and in which they prepare subterranean nests (Naumov 1940, Pisareva 1948, Hamar 1960, Mikeš 1971, Muntyanu 1990, Unterholzner & Willenig 2000, Čanády et al 2005, Hölzl et al 2009, 2011a, b, Szenczi et al 2011, 2012, Simeonovska-Nikolova et al 2014). These mounds have several functions, such as food storage and/or thermoregulation.…”

“…The rebuilding of mounds within three to four days following their destruction by ploughing has also been observed (Muntyanu 1990, Sokolov et al 1990, Čanády et al 2009). The mounds vary in size and composition among geographical locations (Bihari 2004, 2007, Hölzl et al 2009, Szenczi et al 2011, 2012, Simeonovska-Nikolova et al 2014, which may be the result of genetic variation among mice, environmental differences or both. Comparative observations in natural and laboratory conditions (Pisareva 1948, Sokolov et al 1990, Serra et al 2011, Hurtado et al 2013) have shown that the construction of a single mound takes from some days to four weeks.…”

Females prefer cooperative males even when cooperative behavior is unobserved: evidence from the mound-building mouse, Mus spicilegus

“…Choosing a cooperative male could increase females' fitness in several ways. First, since mound size is positively correlated to water-insulation and soil temperature inside the mound (Szenczi et al 2011; Szenczi et al 2012), choosing a male who invests more energy and time in mound building could increase offspring survival during the winter. Second, mound building behavior seems to be genetically heritable (Orsini 1982).…”

“…Previous studies have found that, in captivity, investment in mound building varies between individuals (Simeonovska-Nikolova and Mehmed 2009; Serra et al 2012) and that mound size is highly variable in natural conditions (Holzl et al 2009). Since mound size is positively correlated with water insulation and the soil temperature inside the mound, it is also expected to influence the probability of offspring survival during the winter (Szenczi et al 2011; Szenczi et al 2012). It is therefore likely that females would benefit from choosing a partner that invests greatly in mound building.…”