Movement of Larval Desmognathus quadramaculatus in linear and connected habitats

This dissertation combines observational and experimental studies with computer simulations to study movement of Desmognathus quadramaculatus larvae. I conducted a three-year mark-recapture study that recorded the position of salamander larvae along a headwater stream. A total of 653 individuals were marked. and 211 recaptures involving 156 individuals were made. The mean distance the recaptured larvae traveled was not significantly different than zero. when upstream movements were recorded as negative and downstream movements as positive. All sizes of larvae were able to move upstream and downstream with no apparent bias. This lack of directional bias could imply that headwater populations are connected through the movement of individuals.

To determine if habitat heterogeneity and behavioral interactions could influence movement. I then used the results from the field study to construct an individual-based model to simulate the movements of larval salamanders in replicated heterogeneous landscapes. Habitat heterogeneity and behavior interacted to reduce the number of moves that an individual makes. Dominant individuals moved as often as weaker individuals. but were able to stay in locally high desirable areas longer than subordinate larvae. In an independent test of the model. the model predicted the position of individuals poorly. However, the model successfully predicted the spread of individuals along the stream corridor.

To understand how individuals move between connected streams. I modified the original model to simulate movement between two connected heterogeneous habitats. Population density did not influence speed of colonization or type of individual that colonized the empty area in these simulations. Individual dominance did not significantly affect the average distance moved. The desirability of the area immediately adjacent to the connected habitat was the most important factor in how the empty habitat was colonized. Areas of low desirability adjacent to connected habitats acted as a partial barrier to movement. Since movement of individuals can connect habitats, behavioral interactions and desirability of habitat should be considered when studying how areas or populations exchange individuals.

Spine Title: Movement of larval Dquadramaculatus