Lifespan Analyses of Forest Raptor Nests: Patterns of Creation, Persistence and Reuse

Abstract

Structural elements for breeding such as nests are key resources for the conservation of bird populations. This is especially true when structural elements require a specific and restricted habitat, or if the construction of nests is costly in time and energy. The availability of nesting-platforms is influenced by nest creation and persistence. In a Mediterranean forest in southeastern Spain, nesting-platforms are the only structural element for three forest-dwelling raptor species: booted eagle Aquila pennata, common buzzard Buteo buteo and northern goshawk Accipiter gentilis. From 1998 to 2013, we tracked the fate of 157 nesting-platforms built and reused by these species with the aim of determining the rates of creation and destruction of nesting-platforms, estimating nest persistence by applying two survival analyses, describing the pattern of nest reuse and testing the effects of nest use on breeding success. Nest creation and destruction rates were low (0.14 and 0.05, respectively). Using Kaplan Meier survival estimates and Cox proportional-hazards regression models we found that median nest longevity was 12 years and that this was not significantly affected by nest characteristics, nest-tree dimensions, nest-builder species, or frequency of use of the platform. We also estimated a transition matrix, considering the different stages of nest occupation (vacant or occupied by one of the focal species), to obtain the fundamental matrix and the average life expectancies of nests, which varied from 17.9 to 19.7 years. Eighty six percent of nests were used in at least one breeding attempt, 67.5% were reused and 17.8% were successively occupied by at least two of the study species. The frequency of nest use had no significant effects on the breeding success of any species. We conclude that nesting-platforms constitute an important resource for forest raptors and that their longevity is sufficiently high to allow their reuse in multiple breeding attempts.

Colour plumage polymorphism in the Booted Eagle: inheritance pattern and temporal stability of the morph frequencies

“…In the Ports Natural Park, 17 territories were monitored between 2003 and 2017. In Murcia, 57 territories were monitored between 1995 and 2013 (Jiménez‐Franco, Martínez & Calvo, ). Territory occupation was assessed each year from late March to early May, and based on observed territorial flights, calls and vocalizations, and at least a refurbished nest or direct observation of a female eagle incubating eggs (Jiménez‐Franco, Martínez & Calvo, ).…”

Occupancy modeling reveals territory-level effects of nest boxes on the presence, colonization, and persistence of a declining raptor in a fruit-growing region

“…Increases in anthropogenic land use, particularly agricultural expansion and intensification, pose a significant threat to many species and the functional diversity of species assemblages [ 1 , 2 ]. One form of habitat degradation imposed by human development is the loss of structural resources for nesting, such as cavities or platforms, which are essential for breeding and therefore important for the population dynamics of bird species [ 3 ]. Thus, loss of nest sites in human-modified habitats can negatively affect abundance and diversity of birds [ 4 , 5 ].…”

Vulnerability to geomorphological hazards of an Arctic cliff-nesting raptor, the rough-legged hawk

“…In birds, long-lasting structures are important for reproduction, especially in raptor species (e.g., Sergio et al 2011;Millsap et al 2015). Raptor densities can be limited by the availability of suitable nesting habitat for building such structures (Newton 1979;Wightman and Fuller 2005;Jiménez-Franco et al 2014a). Thus, it is important to better understand how local geomorphology and weather variables influence their persistence.…”