Table 1. Predicted relationships between human and ecological covariates and occupancy and reproduction parameters of Eurasian Eagle-owls in south-eastern Spain.
| Covariate | Description | Hypothesis | Predictions for ecological parameters a |
|---|---|---|---|
| State | Occupancy state of the territory the previous year: 0 (unoccupied), 1 (occupied without breeding success), 2 (occupied with breeding success). | Previous breeding success is positively correlated with a higher territory occupancy rate and reproductive success the following year. | ψ (++), R (++) |
| Survey | Repeated visits to each territory during the breeding period (survey 1- survey 4). | Last surveys are associated with higher occupancy and breeding success detection rates. | ψ (0), R (0) b |
| Year | Breeding season (from 2006 to 2012). | Reproductive success is expected to vary between years. | ψ (0), R (+/-) |
| Zone | The study area is divided into two zones (see Species and Study area section): 1 (northern zone), 0 (southern zone). | The northern zone has a higher availability of prey [42], which is expected to determine a higher probability of territory occupancy and breeding success. | ψ (+), R (+) |
| Ruggedness |
Measured as the standard deviation of altitudes (m) in a 1-km radius plot around the nest, using a 25 m digital elevation model c. | Ruggedness positively influences territory occupancy [36] but negatively influences breeding success [46]. | ψ (+), R (-) |
| Crops | Area covered by agricultural fields in a 1-km radius around nest (m2) d. | Territory occupancy and reproductive success are negatively correlated with the presence of crops around nests. | ψ (-), R (-) |
| Scrub | Area covered by shrub-dominated habitats in a 1-km radius circle around nest (m2) d. | Scrub areas favour rabbit abundance, which positively influences breeding success [47]. | ψ (0), R (+) |
| Distance | Distance from a Eurasian Eagle-owl nest to the nearest road or forest track (m). | The proximity of roads and tracks to nests reduces the probability of territory occupancy and negatively affects breeding success. | ψ (+), R (++) |
a Ecological parameters are probability of occupancy (ψ) and probability of breeding success (R). The strength and direction of predicted trends are indicated with positive and negative signs. The symbol “+/-” indicates that random tendencies are expected in an ecological parameter. Zeros indicate that no relationship between occupancy or breeding success and the predictor is expected.
b Survey is not related to ψ or R but is used to model detection parameters (see the Occupancy models section).
c Data available from 1:25,000 digital elevation model map (MDT25 for Spain) (http://centrodedescargas.cnig.es/CentroDescargas/buscadorCatalogo.do?codFamilia=02107).
d Data available from 1:25,000 CORINE Land Cover 2000 map (I&CLC2000) (http://centrodedescargas.cnig.es/CentroDescargas/buscadorCatalogo.do?codFamilia=02113).