Bursts of speciation have followed colonization of remote oceanic islands by diverse taxa, a process evidenced by island endemics around the world. The present study explores whether the Malvinas -Falkland Islands (MFI), a relatively understudied archipelago off the South Atlantic coast of Patagonia, harbour endemic genetic lineages of passerine birds. Nine passerine species nest regularly in the MFI (Cinclodes antarcticus, Muscisaxicola maclovianus, Troglodytes cobbi, Cistothorus platensis, Turdus falcklandii, Anthus correndera, Melanodera melanodera, Sturnella loyca, and Carduelis barbata). Mitochondrial DNA (cytochrome c oxidase I sequences) are used to quantify and compare divergence between insular and continental populations, finding genetic patterns to vary across these nine species. Most MFI passerines do not show significant genetic differentiation from continental populations, whereas C. platensis, M. melanodera, and T. falcklandii are modestly diverged. Finally, T. cobbi differes markedly from its closest continental relative Troglodytes aedon, a result that is confirmed using nuclear and vocal data. The study also identifies broadly divergent lineages within continental populations of C. platensis and T. aedon. Taken together, these results suggest that the land bird populations of the MFI were established at different times. Troglodytes cobbi is the oldest MFI land bird, splitting from continental T. aedon during the Great Patagonian Glaciation of the Pleistocene.

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SummaryA high proportion of island birds are threatened with extinction as a result of their vulnerability to introduced predators, habitat destruction, and fragmentation/isolation effects. In order to conserve island species effectively, it is necessary to disentangle these effects on distribution and abundance. We attempt to do this for the nine native passerines in the Falkland (Malvinas) Islands, using a database of presence/absence on 59 offshore islands in the archipelago, linked to data for each island on mammal presence, habitat modification, and isolation. Falklands native passerines are of considerable conservation importance, comprising one endemic globally threatened species, several endemic subspecies, and several restricted range species. Presence of rats on islands was by far the most important predictor of passerine presence, overriding the effect of habitat modifications. The globally threatened endemic Cobb's Wren Troglodytes cobbi was absent from all islands containing rats. Some species were more likely, and others less likely to occur on islands where tussac Poa flabellata grassland had been destroyed by grazing. The former species were primarily those adapted to dwarf-heath vegetation, and/or that thrive around human settlements. Island size and isolation were important predictors of occurrence for several bird species. The analyses show that, if vegetation restoration in the Falklands is to meet conservation aims, then it should be accompanied by introduced mammal control. Secondly, they indicate that biogeographical effects on bird distribution among islands in the Falklands are important, and need to be considered when assessing the conservation status of species, and when considering conservation action.

The relative contributions of males and females to incubation, and the diel schedules by which incubation is shared, are important breeding system traits. We used infra-red sensitive cameras to record incubation patterns at 13 nests of the Two-banded Plover Charadrius falklandicus in the Falkland Islands during both day and night. Because predation risk can affect incubation behaviour, we also recorded the diel pattern of nest predation in the wider study population. We found high nest attendance, femalebiased incubation, and strong diel sex-roles, with females incubating during the day and males at night. We also found that incubation intermissions tended to be short but frequent, and were correlated strongly with the diel pattern of nest predations which occurred exclusively in the daylight hours (probably due to the absence of terrestrial mammals from the study site). Our results suggest that sexroles are unusually strict in the Two-banded Plover, and that these strict sex-roles lead to inequality in incubation sharing and the level of exposure to sources of energetic cost such as disturbance by nest predators.

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