TY  - JOUR
A1  - Eccard, Jana
A1  - Fey, Karen
A1  - Caspers, Barbara A.
A1  - Ylönen, Hannu
T1  - Breeding state and season affect interspecific interaction types  indirect resource competition and direct interference
JF  - Oecologia
N2  - Indirect resource competition and interference are widely occurring mechanisms of interspecific interactions. We have studied the seasonal expression of these two interaction types within a two-species, boreal small mammal system. Seasons differ by resource availability, individual breeding state and intraspecific social system. Live-trapping methods were used to monitor space use and reproduction in 14 experimental populations of bank voles Myodes glareolus in large outdoor enclosures with and without a dominant competitor, the field vole Microtus agrestis. We further compared vole behaviour using staged dyadic encounters in neutral arenas in both seasons. Survival of the non-breeding overwintering bank voles was not affected by competition. In the spring, the numbers of male bank voles, but not of females, were reduced significantly in the competition populations. Bank vole home ranges expanded with vole density in the presence of competitors, indicating food limitation. A comparison of behaviour between seasons based on an analysis of similarity revealed an avoidance of costly aggression against opponents, independent of species. Interactions were more aggressive during the summer than during the winter, and heterospecific encounters were more aggressive than conspecific encounters. Based on these results, we suggest that interaction types and their respective mechanisms are not either-or categories and may change over the seasons. During the winter, energy constraints and thermoregulatory needs decrease direct aggression, but food constraints increase indirect resource competition. Direct interference appears in the summer, probably triggered by each individual's reproductive and hormonal state and the defence of offspring against conspecific and heterospecific intruders. Both interaction forms overlap in the spring, possibly contributing to spring declines in the numbers of subordinate species.
KW  - Rodents
KW  - Aggression
KW  - Seasonality
KW  - Space use
KW  - Winter biology
Y1  - 2011
U6  - https://doi.org/10.1007/s00442-011-2008-y
SN  - 0029-8549
SN  - 1432-1939
VL  - 167
IS  - 3
SP  - 623
EP  - 633
PB  - Springer
CY  - New York
ER  - 
TY  - JOUR
A1  - Liesenjohann, Thilo
A1  - Liesenjohann, Monique
A1  - Trebaticka, Lenka
A1  - Sundell, Janne
A1  - Haapakoski, Marko
A1  - Ylonen, Hannu
A1  - Eccard, Jana
T1  - State-dependent foraging: lactating voles adjust their foraging behavior according to the presence of a potential nest predator and season
JF  - Behavioral ecology and sociobiology
N2  - Parental care often produces a trade-off between meeting nutritional demands of offspring and the duties of offspring protection, especially in altricial species. Parents have to leave their young unattended for foraging trips, during which nestlings are exposed to predators. We investigated how rodent mothers of altricial young respond to risk of nest predation in their foraging decisions. We studied foraging behavior of lactating bank voles (Myodes glareolus) exposed to a nest predator, the common shrew (Sorex araneus). We conducted the experiment in summer (high resource provisioning for both species) and autumn (less food available) in 12 replicates with fully crossed factors "shrew presence" and "season." We monitored use of feeding stations near and far from the nest as measurement of foraging activity and strategic foraging behavior. Vole mothers adapted their strategies to shrew presence and optimized their foraging behavior according to seasonal constraints, resulting in an interaction of treatment and season. In summer, shrew presence reduced food intake from feeding stations, while it enhanced intake in autumn. Shrew presence decreased the number of visited feeding stations in autumn and concentrated mother's foraging efforts to fewer stations. Independent of shrew presence or season, mothers foraged more in patches further away from the nest than near the nest. Results indicate that females are not investing in nest guarding but try to avoid the accumulation of olfactory cues near the nest leading a predator to the young. Additionally, our study shows how foraging strategies and nest attendance are influenced by seasonal food provision.
KW  - Myodes glareolus
KW  - Optimal foraging
KW  - Sorex araneus
KW  - Nest protection
KW  - Seasonality
KW  - Interference
Y1  - 2015
U6  - https://doi.org/10.1007/s00265-015-1889-x
SN  - 0340-5443
SN  - 1432-0762
VL  - 69
IS  - 5
SP  - 747
EP  - 754
PB  - Springer
CY  - New York
ER  -