Understanding the spatial dynamics of populations is essential for conservation of species at the landscape level. Species that have adapted to stable environments may not move from their breeding areas even if these have become sub-optimal due to anthropogenic disturbances. Instead, they may breed unsuccessfully or choose not to breed at all. Damara Terns Sternula balaenarum feed off the highly productive Benguela Upwelling System. They breed on the coastal desert mainland of Namibia where development and off-road driving is threatening breeding areas. We report annual survival and breeding dispersal probabilities of 214 breeding adult Damara Terns through capture-mark-recapture at two colonies for 9 years (2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009) in central Namibia. Using multi-state models in program MARK, model selection based on AICc favoured a model that suggests local annual survival of Damara Terns for the dataset was 0.88 (95% CI, 0.73-0.96) and the annual dispersal probability was 0.06 (0.03-0.12). High survival and low dispersal probabilities are consistent with other seabirds adapted to stable environments. These estimates contribute to the first baseline demographic information for the Damara Tern. Low dispersal probabilities indicate that current protection of breeding sites is an important management approach for protecting the species. ZusammenfassungJährliche Ü berlebensrate und Brutortstreuung bei einem an stabile Umweltbedingungen angepassten Seevogel: Auswirkung auf Schutzmaßnahmen Um Arten auf Landschaftsebene zu schützen ist es wichtig, die räumliche Dynamik der Populationen zu verstehen. Es ist möglich, dass Arten, die an eine stabile Umwelt angepasst sind, ihre Brutgebiete nicht verändern können, selbst wenn diese infolge anthropogener Veränderungen nicht mehr optimal sind. Stattdessen könnten sie dort erfolglos zu brüten versuchen oder gar nicht mehr brüten. Damara-Seeschwalben S. balaenarum ernähren sich im hochproduktiven Benguela Auftriebsgebiet. Sie brüten an der Küste der Namibwüste, wo Ü berbauungen und Fahren im Gelände ihre Brutgebiete gefährdet. Wir präsentieren jährliche Ü berlebensraten und Dispersionswahrscheinlichkeiten basierend auf 214 brütenden adulten Damara-Seeschwalben, ermittelt durch Fang-Wiederfang Methoden über neun Jahre Modelle in Programm MARK zeigten für diese Daten, dass die jährliche lokale Ü berlebensrate von Damara-Seeschwalben 0.88 (95% Vertrauernsbereich 0.73-0.96) war und die jährliche Dispersionswahrscheinlichkeit zwischen den Kolonien betrug 0.06 (0.03-0.12). Die hohe Ü berlebensrate und niedrige Dispersionswahrscheinlichkeit sind vergleichbar mit anderen an stabile Umwelten angepassten Seevö-geln. Diese Schätzungen sind ein erster Beitrag zum Verständnis der Demographie von Damara-Seeschwalben. Die niedere Dispersionswahrscheinlichkeiten legen nahe, dass der Schutz der Brutgebiete, wie er momentan betrieben wird, eine tatsächlich wichtige Maßnahme zum Schutz dieser Art ist.
Feeding terns are affected by a variety of environmental conditions. We studied prey capture success of Damara terns Sterna balaenarum in relation to six variables at two breeding colonies in southern Namibia: tidal phase, wind speed, water clarity, cloud cover, water depth and locality. Damara terns dived most successfully at high tide and least successfully at low tide. Prey capture success improved whereas total dive rate decreased with increasing wind speed. Prey capture success was highest in the least turbid water, but was not significantly affected by cloud cover or water depth, and there was no significant difference in dive success between localities. The diet of Damara tern chicks were studied throughout Namibia. Of 55 prey items collected, Cape silverside Atherina breviceps, southern mullet Liza richardsonii and Cape anchovy Engraulis encrasicolus were among the most abundant prey species. At least nine prey species were found in the diet of Damara tern chicks that had not been previously reported from Namibian waters
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