Population dynamics ofClethrionomys glareolus andApodemus flavicollis: seasonal components of density dependence and density independence

Abstract

Population dynamics of Clethrionomys glareolus and Apodemus flavicollis: seasonal components of density dependence and density independence. [In: Theriology at the turn of a new century. J. Gliwicz, ed]. Acta Theriologica 47, Suppl. 1: 39-67.Using long-term data on two forest rodent species [the bank vole Clethrionomys glareolus (Schreber, 1780) and the yellow-necked mouse Apodemus flavicollis (Melchior, 1834)] from the Bia³owie¿a Primeval Forest (E Poland), we decompose the annual density-dependent and density-independent structures into their seasonal components. For this purpose we adopt a state-space modelling approach explicitly incorporating sampling stochasticity. As density-independent factors we use the North Atlantic Oscillation (NAO) -a proxy variable for the overall climatic condition -and data on annual seed production. We find a weak effect of the NAO in the annual models for both species as well as during the winter in the seasonal model for C. glareolus. The effect of the NAO disappears, however, when seed-crops are incorporated into the models (for both the annual and the seasonal -suggesting that NAO primarily affects seed production). Seed production enters the models with a positive effect during the winter only, suggesting that the among-year variation in rodent density is primarily accounted for by differences in seed-production, particularly oak seeds. For A. flavicollis, a slightly positive effect of hornbeam also appears in the summer dynamics. The obtained results are discussed on the basis of earlier studies on the same populations, on the same species studied elsewhere as well as on the basis of general ecological insight.

The Life Cycle of Toxoplasma gondii in the Natural Environment

“…However, other factors may also vary with meteorological conditions and influence T. gondii life cycle. In particular, the population dynamics of rodents is affected by climate-driven vegetation growth [84]. Specifically, when winter is mild, survival is high and rodent populations comprise many adult or old individuals, which are the age groups most often infected.…”

Interaction between seasonal density-dependence structures and length of the seasons explain the geographical structure of the dynamics of voles in Hokkaido: an example of seasonal forcing

“…Although our focus on the seasonal density-dependent structure is similar, the approach taken in this paper is different from that of Hansen et al (1999), Merritt et al (2001) and Stenseth et al (2002), who used data on both spring and autumn densities to assess the seasonal densitydependent structure of the same species. Whereas Hansen et al (1999) and Stenseth et al (2002) made the tacit assumption of the spring and autumn sampling coinciding with the termination of the winter and the summer seasons, we do in this study let the annual density-dependent structure 'tell us' how the year is most appropriately to be divided into two phases (which we will call 'seasons' and refer to as 'summer' and 'winter').…”

“…Whereas Hansen et al (1999) and Stenseth et al (2002) made the tacit assumption of the spring and autumn sampling coinciding with the termination of the winter and the summer seasons, we do in this study let the annual density-dependent structure 'tell us' how the year is most appropriately to be divided into two phases (which we will call 'seasons' and refer to as 'summer' and 'winter').…”

Expansion of great cormorant colony immediately increased isotopic enrichment in small mammals

“…Species-related differences in the isotopic signatures of the two dominant rodent species may be explained by diet differences and microhabitat use, both supporting coexistence (Stenseth et al, 2002;Cassaing et al, 2013). Previous experience with livetrapping and marking of A. flavicollis in the cormorant colony (Jasiulionis, unpubl.)…”