| Publication Type: | Journal Article |
| Year of Publication: | 1998 |
| Authors: | Svensson, BW |
| Journal: | Oikos |
| Volume: | 82 |
| Issue: | 1 |
| Date Published: | 1998 |
| ISBN Number: | 00301299 |
| Keywords: | Falco, Falco rusticolus, Falconidae |
| Abstract: | Dispersal and reproduction were studied in a patchy rock pool population of the long-lived partially bivoltine Gyrinus opacus in south-central Sweden. In most years many pools dry out during spring to early summer triggering adult local dispersal and leading to depopulation of these pools. Dispersal frequency among pools was lower during the prehibernation than during the posthibernation breeding period. On average, each beetle marked as young visited 0.85 pools in addition to their emergence pools. Maximum of eight new pools were visited by an individual beetle. In spite of rather low frequencies of inter-patch movements per beetle a high connectivity between pools was established, consistent with current models of populations inhabiting fluctuating environments. I found no sex difference in average age at leaving the emergence pool, lifetime number of pools visited, lifetime dispersal distance or local emigration and immigration rates. However, females remained for a shorter time in the first new pool visited, immigrated more often into empty pools and performed longer inter-pool movements, while more males showed lifetime site tenacity. There was no priority effect influencing the probability of a beetle becoming a "resident" (staying in the emergence pool until hibernation) or a "disperser'" (leaving the emergence pool before hibernation). Resident pools and dispersal pools were of the same size, but pools where beetles stayed were largely others than those left. On average, resident pools had a higher mean density of G. opacus. There was no difference between prehibernation resident and dispersing females with respect to number of clutches laid, clutch size, or body size. Prehibernation residents, however, had a higher winter survival rate than dispersers, and for females they also lived longer in the study area. In a lifetime perspective, those females achieved the highest reproductive output which combined two strategies, i.e. reproducing and remaining resident during their first season until hibernation, and then leaving the emergence pool in May-June in the subsequent year, spreading their eggs over other pools. |
| URL: | http://www.jstor.org/stable/3546921 |
| Short Title: | Oikos |
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