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Monitoring populations of auklets and other crevice-nesting seabirds remains problematic, although numerous methods have been attempted since the mid-1960s. Anecdotal evidence suggests several large auklet colonies have recently decreased in both abundance and extent, concurrently with vegetation encroachment and succession. Quantifying changes in the geographical extent of auklet colonies may be a useful alternative to monitoring population size directly. We propose a standardized method for colony mapping using a randomized systematic grid survey with two components: a simple presence/ absence survey and an auklet evidence density survey. A quantitative auklet evidence density index was derived from the frequency of droppings and feathers. This new method was used to map the colony on St. George Island in the southeastern Bering Sea and results were compared to previous colony mapping efforts. Auklet presence was detected in 62 of 201 grid cells (each grid cell = 2500 [m.sup.2]) by sampling a randomly placed 16 [m.sup.2] plot in each cell; estimated colony area = 155 000 [m.sup.2]. The auklet evidence density index varied by two orders of magnitude across the colony and was strongly correlated with means of replicated counts of birds socializing on the colony surface. Quantitatively mapping all large auklet colonies is logistically feasible using this method and would provide an important baseline for monitoring colony status. Regularly monitoring select colonies using this method may be the best means of detecting changes in distribution and population size of crevice-nesting seabirds. Key words: Aethia pusilla, Bering Sea, colony mapping, crevice-nesting seabird, Least Auklet, population monitoring. El seguimiento de las poblaciones de especies del genero Aethia y de otras ayes marinas que anidan en agujeros ha sido problematico a pesar de que numerosos metodos se han evaluado desde mediados de la decada de 1960. La cuantificacion de los cambios en la extension geografica de las colonias de especies del genero Aethia podria ser de utilidad como una alternativa que no requiere medir directamente el tamano poblacional. Se describe un metodo estandarizado para el mapeo de colonias utilizando una prospeccion sistematica de cuadriculas aleatorias. El monitoreo consta de dos componentes: una prospeccion simple de presencia/ausencia y una prospeccion de la densidad de rastros de las especies de Aethia mediante un indice cuantitativo derivado de residuos fecales y/o plumas. Los resultados del mapeo de la colonia en la Isla San Jorge, ubicada en el sureste del Mar de Bering, usando este nuevo metodo, fueron comparados con los intentos previos de mapear las colonias. Dentro de circulos de 16 [m.sup.2] colocados aleatoriamente en la colonia, se detecto la presencia de especies del genero Aethia en 62 de un total de 201 cuadriculas (tamano de la cuadricula = 2500 [m.sup.2]; area estimada de la colonia = 155 000 [m.sup.2]). El indice de densidad de rastros en la colonia de Aethia vario en dos ordenes de magnitud. El indice de densidad de rastros y los promedios de conteos repetidos de aves que se encontraban socializando en la superficie de la colonia estuvieron fuertemente correlacionados. El mapeo cuantitativo de grandes colonias de Aethia utilizando este metodo es logisticamente factible, y podria proporcionar una base importante para el monitoreo de la condicion de las colonias de Aethia a lo largo del tiempo. Realizar monitoreos a largo plazo de colonias especificas usando este metodo podria ser la mejor solucion para detectar cambios en la distribucion y el tamano de las poblaciones.

Aleutian Tern Onychoprion aleuticus numbers in Alaska appear to be in decline; however, colonies are difficult to count for the purposes of monitoring due to their co-occurrence with Arctic Terns Sterna paradisaea, low nesting densities, high variability in attendance, sensitivity to human disturbance, and remote terrain. We paired visual observations with unmanned aerial systems (UASs) to test the feasibility of using this technology to survey a small colony of nesting Arctic and Aleutian terns in southcentral Alaska. We used counts of terns in the air and nest attendance to test for disturbance from UAS flights. We conducted 11 UAS flights over seven days at altitudes ranging from 15-30 m and located 23 nests in the 4.1 ha (0.041 km²) colony site (5.6 nests ha-1) by systematically searching the orthomosaics. We were most likely to distinguish tern species in the 18-m and 15-m altitude photos; the white forehead was most visible in side angle rather than top-down. Nest attendance and the number of aerial birds were not influenced by the UAS in this colony, which experiences high Larus gull activity. Aleutian Terns arrived on 19 May and were attending nests by 02 June; nest attendance declined throughout June. We believe the best approximation of total nesting pairs will be achieved by counting nests 7-10 d after first initiation. In mixed species colonies, we recommend that UASs fly in a 'lawn mower' pattern with overlap to maximize side angle images and aim for an image resolution of < 4 mm (which was achieved by 15-m altitude flights with our camera setup). In single species colonies, 30 m is sufficient and can be achieved more efficiently. [ABSTRACT FROM AUTHOR]

We compiled survey data on 202 Aleutian Tern colonies throughout Alaska and Russia to assess the current status and colony sizes and to evaluate whether there had been changes in recent decades. We fit a Poisson generalized linear mixed model to all available counts of Alaskan colonies since 1960, excluding colonies in which the temporal spread of counts was < 6 years. Russian data were not included in the trend model due to our inability to resolve dates on a number of counts. We estimate that numbers at known colonies in Alaska have declined 8.1% annually since 1960 or 92.9% over three generations (33 years; 95% CI = 83.3%-97%), with large colonies experiencing greater declines than small colonies. Trends at known colonies within discrete geographic regions of Alaska (Aleutian Islands, Bering Sea, Chukchi Sea, Gulf of Alaska and Kodiak Island) were consistently negative. The most recent counts of all known Alaskan colonies summed to 5 529 birds. This estimate should be considered a rough minimum because it does not account for colonies that have not been surveyed in recent years -- the size of which may have changed -- or for the fact that the surveys conducted were neither systematic nor inclusive of all potential habitats. In Russia, the sum of the most recent count of all colonies was 25 602 individuals, indicating that Russia may host approximately 80% of the world population. Numbers in some regions in Russia appear to have increased substantially in recent decades, especially on Sakhalin Island and the southern coast of the Koryak Highland. We have no data to identify any population-level stressor that could explain the apparent reduction in numbers in Alaska. However, predation, egging and other anthropogenic disturbances, and degraded habitat may cause population change at local levels. If this overall pattern cannot be explained by other possible but unlikely factors (e.g. establishment of large colonies in new locations within Alaska, or major shifts between Alaska and Russia), then the observed trends in Alaska are, indeed, alarming. Therefore, we urge close monitoring of known colonies within Alaska, studies of dispersal, establishment of management practices to insulate colonies from human disturbance, and more concerted efforts among Alaskan and Russian partners. [ABSTRACT FROM AUTHOR]

The article presents a study which estimated the number of Least Auklets attending the colony on Saint George Island, Alaska. The researchers made a photo count of the bird species attending the inland colony at Ulakaia Ridge during an unusually late snow cover in 2008. They estimated the population of birds in the colony to be around 88,263 on May 15, 2008. According to them, the count that they recorded likely represented almost the entire population breeding at the colony that year because of the known life history of the species.

The 1800-km-long Aleutian Archipelago is a breeding area for more than 10 million seabirds of 26 species. We evaluated the distribution of breeding colonies of 24 common breeding species in relationship to ocean passes of two sizes, availability of nesting habitat and the distribution of introduced predatory mammals. Further, we evaluated population trends and reproductive rates to amplify information about distribution. We compared distributions and demographic parameters based on proposed differences in marine habitats in the eastern, central and western Aleutians. Samalga Pass did not appear to be a break point for breeding seabird distribution as is suggested for oceanographic characteristics and other species groups by papers in this volume. Factors affecting distribution varied with foraging and nesting strategies of various species groups. The three largest breeding aggregations of seabirds in the Aleutians (Buldir, Chagulak and Kiska) all have relatively high species diversity and are located next to large passes. However, when other predictors were considered, proximity to medium or large passes was important mainly for surface-feeding piscivores. The extent of nesting habitat apparently does not limit the distribution of surface- or burrow-nesting species (including planktivores and piscivores). Instead, the distribution of these species probably has been shaped by introduced mammals. Nesting habitat for ledge- and crevice-nesting species is more limited than for surface and burrow nesters but is still fairly widespread. Ledge- and crevice-nesting species are less susceptible to fox predation than are surface and burrow nesters. These species may have been reduced by predation but were not extirpated. [ABSTRACT FROM AUTHOR]