LE3 .A278 1998

1998

Taylor, Phil

Acadia University

Master of Science

Masters

Biology

Biology

I explore the effect of landscape structure, arising from forest fragmentation, on the fine-scale movement behaviours of two congeneric damselfly species--Calopteryx aequabilis and Calopteryx maculata. I compare patterns of distribution and movement behaviours across three kinds of landscape: unfragmented, where breeding resources (streams) are adjacent to foraging resources (forest); moderately fragmented, where breeding and foraging resources are disjunct; highly fragmented, where few foraging resources are available. I compare damselfly distribution among stream and forest habitat on landscapes that differ in amount of forest fragmentation. I demonstrate that patterns of damselfly distribution among habitats differ among landscape types, for both species. C. aequabilis is most abundant on moderately and highly fragmented landscapes, whereas, C. maculata is most abundant on unfragmented and moderately fragmented landscapes. Neither species accesses forest habitat on highly fragmented landscapes. These results indicate that both species alter their movement behaviour on highly fragmented landscape. I then compare fine-scale movement behaviours of the two species on different landscapes. I show that rates of movement and the propensity to move away from streams differ, for both species, among landscapes. Most importantly, neither species moves away from streams on highly fragmented landscapes. I also show that neither species tends to make directed movements, even when they move away from streams on moderately fragmented landscapes. This suggests that fine-scale movement behaviours on fragmented landscapes are simply extensions of pre-existing behaviours. I demonstrate a mechanistic link between C. maculata fine-scale movement behaviour and its broader-scale pattern of distribution on different landscapes. This result is significant because it demonstrates that some responses to spatial heterogeneity (i.e., movement behaviours) can be extrapolated across scales in a straightforward manner.

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