Resumen de Economical versus ecological development: a case study of white storks in a cattle farm
Pablo Vergara, José Ignacio Aguirre, Juan Antonio Fargallo Vallejo
Aims: Wildlife and humans compete for natural resources generating conflicts that sometimes translate into financial loss. In this study, the economical costs of the upkeep of a white stork Ciconia ciconia colony at a cattle farm over a six-year period were evaluated. Furthermore, the effect of ash lopping in nest site selection and the efficacy of nest removal in controlling the population of this species was analysed.
Location: The ash dehesa studied was located in the Northern area of the Madrid province, in both Soto del Real and Manzanares el Real localities (40º 44' N, 3º 49' E), from 1999 to 2004.
Methods: Estimation was made of the economical cost of white stork colony maintenance by estimating the total weight of branches and bud shoots on the ashes. The tree type (lopped or unlopped) was noted to determine nest site selection where new nests were established in the subsequent year after lopping. Finally, it was recorded if removed nests (by the Regional Government as a method of population control) were less like to rebuilt in function of previous breeding success (failed or not).
Results: Storks mainly selected lopped trees as nest sites. To avoid the increase of white stork pairs in the colony, lopping was not carried out in subsequent years, causing economical losses to landowners (a minimum of 13,902.33 ¿ in six years). In addition, due to the high nest-site fidelity in this species, the total number of nests in the colony was not reduced by nest removal. Nests that contained a pair that failed in their reproductive attempt were less likely to be rebuilt in the consecutive breeding season. The results showed that selective nest removal (removal of nests which failed the previous year) might be a more effective method for population control than nest removal methods used to date.
Conclusions: Due to the low total economic cost of colony maintenance, it is proposed that economical compensation by the regional government to the farm owners will be a more effective management measure than nest removal.
