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We studied factors affecting breeding habitat selection in a population of cliff-nesting peregrines Falco peregrinus across multiple spatial levels (cliff site, cliff context and land-use of the surrounding landscape), over a 2,100 km 2 study area in the Alps (Italy and Switzerland). We detected 30 breeding pairs (density: 1.43 territorial pairs/100 km 2 ), whose territories were uniformly distributed over the study area. We compared 15 habitat features characterising occupied cliffs and 30 randomly selected unoccupied cliffs by means of stepwise forward logistic regression and hierarchical partitioning. The logistic regression analysis showed that occupied cliffs were longer (horizontal length), steeper, and had a greater extension of urban areas in the surrounding landscape compared to non-occupied cliffs. The model had a discrimination ability of 0.95. Hierarchical partitioning indicated that the logistic regression model was appropriate. Neither the distance of cliffs to the nearest site occupied by a potential competitor and predator, the eagle owl Bubo bubo, which occurred at a low density (0.67 pairs/100 km 2 ), nor the distance to the nearest site occupied by peregrines had any effect on the cliff suitability model. Therefore, habitat selection in cliff-nesting peregrines was mainly influenced by cliff site features and surrounding landscape characteristics, whereas the proximity to conspecifics and to an intraguild predator had no apparent effects on peregrine settlement in our study population.

Many functions in behavioural processes of small passerines are regulated via vocal messages. Song plays an important role in the development of reproductive barriers and thus playback experiments can often be used for investigating the potential for reproductive isolation through behavioural mechanisms. Moltoni’s warbler Sylvia (cantillans) moltonii is characterized by diagnostic vocalizations and a peculiar pattern of distribution, being parapatric and partly sympatric with the nominate Sylvia c. cantillans. With this work, we test whether these two closely related taxa react equally to their own song and to the song of the other taxon, shedding light on whether they perceive each other’s songs as coming from the same species. We carried out 184 playback experiments within the mainland range of the two forms. We judged the response of the bird on a scale of scores. Each taxon responded more strongly to playback when faced with the song of its own taxon. This held true when applied only to males or females. Additionally, birds tested for both songs showed a stronger response to the song of their own taxon. The distributional context (sympatry vs. allopatry) did not affect bird response. Results indicate that a certain degree of reproductive isolation between the two taxa (because of diverged mate recognition systems) already exists; consistently with genetic data and with the peculiar pattern of distribution; this suggests that the two taxa have reached species status.

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