topography and human influence) than those existing within the central mountain
range. Human presence is known to strongly affect the distribution patterns of
bearded vultures and other large raptors, not only respect to the safety of breeding
nest sites (Donázar et al. 1993; Margalida et al. 2007a), but also with regard to
foraging grounds (Bautista et al. 2004; Gavashelishvili and McGrady 2006).
Previous analyses have shown that the breeding success of Pyrenean bearded
vultures is affected by human activities and infrastructures (Donázar et al. 1993;
Arroyo and Razin 2006) as occurs in other vulture species (Zuberogoitia et al. 2008;
Margalida et al. 2011b; but see Oppel et al. 2016). Therefore, it is reasonable to
think that the low probability of cliff occupancy outside the Pyrenees is determined,
at least partially, by the intense human influence on these peripheral mountain
regions. In this sense, the Pyrenees could progressively become more of an ecological island for the bearded vulture surrounded by areas that are inadequate due to
the increasingly human influence on the environment. If these factors prevent the
population from increasing in numbers and expanding, the risk of extinction in this
population will remain high as a consequence of stochastic demographic and
environmental phenomena and the limited genetic variability (Godoy et al. 2004).
The relatively low quality of sites in nearby mountains may prevent the
expansion of the breeding range, but conspecific attraction and supplementary
feeding may also play a role. Our study confirmed that monitoring changes in key
variables relevant to habitat selection are useful in determining long-term trends in
settlement patterns in heterogeneous environments. The results also suggest that the
available nest-site selection model may accurately predict cliff occupancy by
bearded vultures in those areas where the distance to the nearest neighbour is not
limiting. In particular, the model may be useful in establishing priority areas for
reintroduction.
15.4 Changes in Mating System and Population
Regulation
15.4.1 Cooperative Breeding
In many bird species, a proportion of mature individuals in the population does not
breed (i.e. floaters), mainly because all suitable territories are occupied (Newton
1992). These individuals are a reservoir for the recruitment of new breeders and,
therefore, are important for the regulation of the population (López-Sepulcre and
Kokko 2005). However, delaying reproduction has a fitness cost, even for a
long-lived species, and mature birds may try to enter into the reproductive population by alternative routes: individuals may occupy poor-quality territories
(Rodenhouse et al. 1997), or enter into an occupied high-quality territory as a helper
(Hatchwell and Komdeur 2000).
15 Importance of Long-Term Studies to Conservation …
349
range. Human presence is known to strongly affect the distribution patterns of
bearded vultures and other large raptors, not only respect to the safety of breeding
nest sites (Donázar et al. 1993; Margalida et al. 2007a), but also with regard to
foraging grounds (Bautista et al. 2004; Gavashelishvili and McGrady 2006).
Previous analyses have shown that the breeding success of Pyrenean bearded
vultures is affected by human activities and infrastructures (Donázar et al. 1993;
Arroyo and Razin 2006) as occurs in other vulture species (Zuberogoitia et al. 2008;
Margalida et al. 2011b; but see Oppel et al. 2016). Therefore, it is reasonable to
think that the low probability of cliff occupancy outside the Pyrenees is determined,
at least partially, by the intense human influence on these peripheral mountain
regions. In this sense, the Pyrenees could progressively become more of an ecological island for the bearded vulture surrounded by areas that are inadequate due to
the increasingly human influence on the environment. If these factors prevent the
population from increasing in numbers and expanding, the risk of extinction in this
population will remain high as a consequence of stochastic demographic and
environmental phenomena and the limited genetic variability (Godoy et al. 2004).
The relatively low quality of sites in nearby mountains may prevent the
expansion of the breeding range, but conspecific attraction and supplementary
feeding may also play a role. Our study confirmed that monitoring changes in key
variables relevant to habitat selection are useful in determining long-term trends in
settlement patterns in heterogeneous environments. The results also suggest that the
available nest-site selection model may accurately predict cliff occupancy by
bearded vultures in those areas where the distance to the nearest neighbour is not
limiting. In particular, the model may be useful in establishing priority areas for
reintroduction.
15.4 Changes in Mating System and Population
Regulation
15.4.1 Cooperative Breeding
In many bird species, a proportion of mature individuals in the population does not
breed (i.e. floaters), mainly because all suitable territories are occupied (Newton
1992). These individuals are a reservoir for the recruitment of new breeders and,
therefore, are important for the regulation of the population (López-Sepulcre and
Kokko 2005). However, delaying reproduction has a fitness cost, even for a
long-lived species, and mature birds may try to enter into the reproductive population by alternative routes: individuals may occupy poor-quality territories
(Rodenhouse et al. 1997), or enter into an occupied high-quality territory as a helper
(Hatchwell and Komdeur 2000).
15 Importance of Long-Term Studies to Conservation …
349