Population trends of the Galapagos penguin: impacts of El Nino and La Nina

Article Abstract:

The current population of Galapagos penguins is estimated between 4,250 and 8,500, declining by half from its level in the early 1970s. The variation and decline in population size is hypothesized to be due to significant changes in oceanic conditions, since cold surface water conditions or La Nina enhance body condition, while warming of surface waters or El Nino causes it to deteriorate. Its population is found to have fluctuated, declining to an alarming level after the 1982-83 El Nino but which since then has recorded a slow recovery.

Penguins, Galapagos Islands

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Dispersal and population structure in the European Starling

Article Abstract:

Bird dispersal can be estimated using banding data and genetic data. Both methods were used to estimate the dispersal and genetic population structure in the European Starling in North America. Banding data suggest fairly high natal dispersal. Genetic data, based on populations in Vermont, Colorado, California and Virginia were found to be consistent with those species with large demes and high dispersal rates.

Behavior, Animals, Animal dispersal, Starlings

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Density and roost site characteristics of Spotted Owls in the Sierra Madre Occidental, Chihuahua, Mexico

Article Abstract:

The roosting habitat and density estimates of Mexican Spotted Owls were investigated in randomly chosen quadrats in the Sierra Madre Occidental of southwestern Chihuahua, Mexico. Findings showed that owls roost mostly in medium-sized trees. Spotted Owl roosts are mostly found in steeper slopes, more canopy layers, bigger canopy closure and bigger live tree basal area compared to random sites.

Environmental aspects, Habitat (Ecology), Habitats, Owls, Spotted owl, Spotted owls, Chihuahua, Mexico

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