Natura Pitiusa

Owing to increasing population trends and facultative predatory habits, large gulls have been identified as significant agents of change in the alteration of many ecological communities. Often, they are perceived as negatively impacting the population trends of most sympatric waterbirds. Consequently, culling programs have been implemented to remove adults, chicks and eggs intensively. Here, we review the interactions recorded in the literature between the yellow-legged gull Larus michahellis and 10 sympatric waterbirds in the Mediterranean region, all threatened and classified as species of conservation concern. We also used 177 long-term population trends derived from previous studies to study the population dynamics of these species and the culling effort performed. We show that gulls negatively affected survival, fecundity, foraging ecology and nesting habitat availability for many species. However, the annual population growth rates of most sympatric waterbirds showed positive

It is often assumed that conservation actions targeting a threatened community (e.g. habitat protection) will result in similar benefits for all species. However, complex interactions between species, such as interference competition, may result in displacement of subordinate, vulnerable species. We analysed here the spatio-temporal population dynamics of a threatened seabird community since the protection in the 1980s of several breeding sites at the Ebro Delta, western Mediterranean, Spain during 1980–2007. Competition for the most suitable patches was governed by body size, with smaller species avoiding associations with larger, dominant species. We tested whether the density increase of the larger species (yellow-legged gull Larus michahellis and Audouin’s gullLarus audouinii) at La Banya (the highest quality patch within the Delta) affected species diversity at the local level. As expected, such diversity decreased, resulting also from the colonisation of other sites by smaller

Del Moral, J. C. (Ed.). 2008. El halcón de Eleonora en España. Población en 2004-2007 y método de censo . SEO/BirdLife. Madrid.

RESUMEN Se dan a conocer algunas especies interesantes para las Baleares y también alguna especie nueva para la Flora insular como Riega helicophylla Mont. Cros, R.M. (1982) Acta Botánica Malacitana, 7

Resumen: Una serie de recolecciones realizadas en la isla de Ibiza han supuesto un incremento de 9 especies al catálogo de briófitos de esta isla, de las cuales Entosthodon schimperi Brugués es nueva para el archipiélago balear. Montserrat Brugués, Elena Ruiz, Anna Barrón & Llorenç Sáez (2010) Bol. Soc. Esp. Briol. 34/35: 61-65 (2010)