Mon, Aug 02, 2021:On Demand
Background/Question/Methods
The relationship between the home range of an animal and the spatio-temporal distribution of resources is well established and widely accepted in animal systems. The resource dispersion hypothesis (RDH) is an elegant model that encompasses the link between animal behavior's ecological and sociological aspects. The RDH assumes that when there is high spatio-temporal heterogeneity in resources, even a single animal (or the primary occupants) will need a larger enough area (home range) to meet its energetic requirements at a given time. Thus, under such conditions, the economics of exploiting these resource patches enable several individuals to share resources over a common area, satisfying their resource needs without imposing high costs on each other. RDH thus, would have four predictions; a) home range size (HR) of an animal will be determined by the dispersion of resources (RD) , b) group size will be determined by the resource richness (RR) , c) group size will be determined by resource heterogeneity, and given the above predictions hold true, d) group size (GS) will remain independent of the home range size. In a peri-urban neighbourhood of a metropolitan city, Bengaluru (India), we test RDH predictions in free-ranging dogs (FRD). In a delineated area of 4 sq. km, we used a four-sample method of photographic mark-recapture. We collected geospatial data on FRD and information on age, sex, coat coloration, body conditions, etc. Information on discernable resources was recorded within this area using spatial data.
Results/Conclusions We found that the spatial distribution of FRDs and resources within the study area were strongly correlated across seasons (p < 0.0001). Tests for RDH indicated that in a peri-urban system, the assumptions of RDH were only partially satisfied (as most previous studies), where RD was correlated to HR only in winter but not summer, and GS was independent of HR across both seasons. Although the reason for this was not apparent, it could be that due to extreme heterogeneity in resource distribution patterns over space and time, it was almost impossible to account for all the available resources in an urban system. Furthermore, using network analysis and modularity assessment, we found that the groups were extremely modular, suggesting that the fission-fusion strategy might be operating among these groups, as larger groups may split up into smaller subgroups at an unidentifiable threshold of resources.
Results/Conclusions We found that the spatial distribution of FRDs and resources within the study area were strongly correlated across seasons (p < 0.0001). Tests for RDH indicated that in a peri-urban system, the assumptions of RDH were only partially satisfied (as most previous studies), where RD was correlated to HR only in winter but not summer, and GS was independent of HR across both seasons. Although the reason for this was not apparent, it could be that due to extreme heterogeneity in resource distribution patterns over space and time, it was almost impossible to account for all the available resources in an urban system. Furthermore, using network analysis and modularity assessment, we found that the groups were extremely modular, suggesting that the fission-fusion strategy might be operating among these groups, as larger groups may split up into smaller subgroups at an unidentifiable threshold of resources.