The breeding biology of the endemic Berthelot's Pipit Anthus berthelotii in a harsh oceanic island environment (Tenerife, Canary Islands).

We describe the density, breeding and foraging ecology of the Berthelot's Pipit (Anthus berthelotii), an endemic passerine to the Atlantic islands, in the semi-arid coastal scrub of Tenerife. Furthermore, we analyse the effects of temperature and rainfall in the onset of reproduction and the behaviour (nest site and foraging site selection). The average density of the Pipit (using DISTANCE methodology) in the semi-arid coastal scrub was 7.1 birds 10ha-1, and the overall density estimate in grassland was 3.3 birds 10ha-1. The Pipit bred early (mean average first-egg laying date 12 February) and in response to rainfall (but not temperature). By the Mayfield method, the probability of the nests surviving the egg stage was 0.77 and of and the nests surviving the chick stage 0.67 - assuming an incubation period of 13 days and a chick stage of 12.5 days - based on the European average for the similar-sized Meadow Pipit Anthus pratensis. Overall nest survival pooling stages were 0.51. The Pipits had a low clutch size (3.3 eggs, range of 2-4). Nest damage by heavy rainstorms was the major cause of nest failures (three out of five failures). The Pipits nested preferentially in grass with relatively low densities of Euphorbia balsamifera bushes. Birds selected grassy areas as their main foraging site but also preferred to forage on large rocks during nesting: caterpillars were the main food items (14 out of 17 prey captures). [ABSTRACT FROM AUTHOR]