Habitat selection by the swamp wallaby (Wallabia bicolor) in relation to diel period,food and shelter

Patterns of resource selection by animals may be influenced by sex, and often change over a 24‐h period. We used a dry sclerophyll landscape managed for commercial timber production to investigate the effects of sex and diel period on habitat selection by the swamp wallaby (Wallabia bicolor). We predicted that selection would be (i) affected by both sex and diel period; and (ii) positively related to lateral cover during the day, but to food resources at night. Non‐metric multidimentional scaling indicated that some of the available habitats differed markedly with respect to visibility (an indicator of lateral cover), fern cover, forb cover, wallaby density and a forage quality index, providing the basis for non‐random habitat selection. At the landscape scale, wallabies showed strong selection for 5‐year‐old regenerating sites, selected against 10‐year‐old regenerating sites and unharvested forest, and avoided recently harvested (3–10 months post‐harvest) sites completely. At the scale of individual home ranges, a pooled male and female sample demonstrated selection for unharvested forest over recently harvested sites during both diurnal and nocturnal periods. A separate analysis showed that both sex and diel period influenced the selection of 5‐ and 10‐year‐old sites and the surrounding unharvested forest. Using a novel approach, we demonstrated that diurnal habitat selection by both sexes was negatively correlated with visibility, representing stronger selection for areas with more lateral cover. Nocturnal selection by females was positively correlated with values of a forage quality index, but this was not the case for males. We hypothesise that the observed patterns of selection were driven by the need to find food and avoid predators, but were also affected by the different reproductive strategies of males and females. Our results demonstrate the importance of incorporating factors such as sex and diel period into analyses of habitat selection.     

Phonotaxis and aggression in the coneheaded katydid Neoconocephalus affinis

ABSTRACT. Positive phonotaxis to tape recorded conspecific song by males of the katydid Neoconocephalus affinis (Beauvois) (Orthoptera: Tettigoniidae) was studied in the field, in Puerto Rico. N.affinis males stridulated loudly during evening hours, and most males were territorial. Aggression between neighbours occurred, albeit rarely, and playback experiments using tape recordings of N.affinis song showed that aggressive behaviour, in the form of jumps directed toward a loudspeaker, could be elicited from a male by song broadcast above a threshold sound intensity. Response thresholds for different males varied from 76 to 93 dB, intensities that corresponded to calculated inter-neighbour distances of 1.6-0.26 m, respectively. Insects that had lower response thresholds were on average more isolated from neighbours and also stridulated more persistently and at a higher sound intensity than insects with higher response thresholds. N.affinis males displayed no phonotaxis toward the song of Neoconocephalus maxillosus , a sympatric species whose song is similar to that of N.affinis in principal frequency but differs in wingstroke rate. Phonotaxis toward conspecific song could only be elicited from males while they were silent.