15.7 Effects of Changes in Sanitary Policies
in Demographic Parameters
Any factor that disturbs the balance between fecundity and survival will be particularly hazardous for species with slow lifestyles (Owens and Benett 2000;
Cardillo et al. 2004). For example, the recent and sudden appearance of non-natural
mortality factors related to the ingestion of veterinary drugs (i.e. diclofenac) or the
increase in the use of illegal poison baits severely affected populations of Old
World vultures (Green et al. 2004, 2006; Virani et al. 2011; Margalida 2012;
Margalida et al. 2014c). In parallel, a recent change in European health policy may
be exacerbating the precarious status of these large species. Coinciding with the
outbreak of bovine spongiform encephalopathy in 2001, scavenger food resources
have been reduced because farmers were forbidden from retaining certain dead
livestock (Donázar et al. 2009a; Margalida et al. 2010).
Considering the importance of such information for managers and conservationists, our purpose was to test if two human-induced activities (i.e. illegal use of
poison baits and regulations in the availability of domestic carcases) can modify
life-history traits in a threatened vulture population. Some assessment of food
resources and their relation to population dynamics (Colomer et al. 2011; Margalida
et al. 2011a; Margalida and Colomer 2012; Martínez-Abraín et al. 2012) and
behavioural changes (Zuberogoitia et al. 2010; Margalida et al. 2011d, 2014b) has
been documented. In this sense, although food availability can also influence
life-history traits and the scientific literature on this topic in birds is abundant (Lack
1968; Western and Ssemakula 1982; Oro et al. 1999, 2004), to our knowledge few
studies have attempted to relate the effects of human-induced activities on
life-history traits in long-lived raptor species (Martínez-Abraín et al. 2012,
Hernández-Matías et al. 2015). The outbreak of bovine spongiform encephalopathy
began in 2001, the restrictive legislation forced the closure of 80% of feeding
stations (Donázar et al. 2009a; Cortés-Avizanda et al. 2010; Margalida et al. 2014b)
and obliged the collection of domestic ungulates to be destroyed. These measures
were not implemented effectively until 2005 (Donázar et al. 2009a, 2010;
Margalida et al. 2010) when the recovery of dead livestock was collected from
farms and most of the feeding stations (80%) closed. Thus, we considered the
period 1994–2004 as the “before policy implementation period” (noted as BPI) and
2005–2011 the “after policy implementation period” (noted as API) (Margalida
et al. 2012). During the BPI remains of domestic ungulates were present in the field
and food availability was considered sufficient to cover the energetic requirements
of avian scavengers (Margalida et al. 2011a). However, during API the carcases of
domestic animals progressively had to be collected from farms and destroyed in
authorised plants (Donázar et al. 2009a; Morales-Reyes et al. 2015). The monitoring of several regions suggested that more than 80% of remains of Ovis/Capra
were collected, whereas this proportion reached nearly 100% for the remains of
Bos/Equus.
15 Importance of Long-Term Studies to Conservation …
367
in Demographic Parameters
Any factor that disturbs the balance between fecundity and survival will be particularly hazardous for species with slow lifestyles (Owens and Benett 2000;
Cardillo et al. 2004). For example, the recent and sudden appearance of non-natural
mortality factors related to the ingestion of veterinary drugs (i.e. diclofenac) or the
increase in the use of illegal poison baits severely affected populations of Old
World vultures (Green et al. 2004, 2006; Virani et al. 2011; Margalida 2012;
Margalida et al. 2014c). In parallel, a recent change in European health policy may
be exacerbating the precarious status of these large species. Coinciding with the
outbreak of bovine spongiform encephalopathy in 2001, scavenger food resources
have been reduced because farmers were forbidden from retaining certain dead
livestock (Donázar et al. 2009a; Margalida et al. 2010).
Considering the importance of such information for managers and conservationists, our purpose was to test if two human-induced activities (i.e. illegal use of
poison baits and regulations in the availability of domestic carcases) can modify
life-history traits in a threatened vulture population. Some assessment of food
resources and their relation to population dynamics (Colomer et al. 2011; Margalida
et al. 2011a; Margalida and Colomer 2012; Martínez-Abraín et al. 2012) and
behavioural changes (Zuberogoitia et al. 2010; Margalida et al. 2011d, 2014b) has
been documented. In this sense, although food availability can also influence
life-history traits and the scientific literature on this topic in birds is abundant (Lack
1968; Western and Ssemakula 1982; Oro et al. 1999, 2004), to our knowledge few
studies have attempted to relate the effects of human-induced activities on
life-history traits in long-lived raptor species (Martínez-Abraín et al. 2012,
Hernández-Matías et al. 2015). The outbreak of bovine spongiform encephalopathy
began in 2001, the restrictive legislation forced the closure of 80% of feeding
stations (Donázar et al. 2009a; Cortés-Avizanda et al. 2010; Margalida et al. 2014b)
and obliged the collection of domestic ungulates to be destroyed. These measures
were not implemented effectively until 2005 (Donázar et al. 2009a, 2010;
Margalida et al. 2010) when the recovery of dead livestock was collected from
farms and most of the feeding stations (80%) closed. Thus, we considered the
period 1994–2004 as the “before policy implementation period” (noted as BPI) and
2005–2011 the “after policy implementation period” (noted as API) (Margalida
et al. 2012). During the BPI remains of domestic ungulates were present in the field
and food availability was considered sufficient to cover the energetic requirements
of avian scavengers (Margalida et al. 2011a). However, during API the carcases of
domestic animals progressively had to be collected from farms and destroyed in
authorised plants (Donázar et al. 2009a; Morales-Reyes et al. 2015). The monitoring of several regions suggested that more than 80% of remains of Ovis/Capra
were collected, whereas this proportion reached nearly 100% for the remains of
Bos/Equus.
15 Importance of Long-Term Studies to Conservation …
367