Site fidelity and territorial behaviour of some migratory passerine species overwintering in the Mediterranean area

• Autores: Mariano Cuadrado
• Directores de la Tesis: Sören Svensson (dir. tes.)
• Lectura: En la Lund University ( Suecia ) en 1995
• Idioma: inglés
• Número de páginas: 101
• Enlaces
  • Tesis en acceso abierto en: Dialnet
• Resumen

  • Three species (Blackcaps, Sylvia atricapilla, Robin Erithacus rebecula and Black Redstart Phoenicurus ochrurus) were studied at five sites in Spain during winters 1981-84 and 1989-1994. Some birds exhibited winter site fidelity. Recoveries occurred mostly within the same winter of ringing. However, some birds were recorded after 5, 3 and 2 yrs, in the three species respectively, in the same area. In Blackcaps, the comparison of the annual survival estimates from two ringing sites (0.47 and 0.49) and the whole Spanish over-wintering population (0.48) suggest site fidelity for most surviving migratory Blackcap in winter.

    Black Redstars showed a complex territorial system with birds defending 1) stable or 2) temporary territories and 3) birds that did not defend territories (floaters). Both territorial and non-territorial birds seemed to be resident in the area throughout the winter. No differences in morphology or body condition were recorded between territorial and non-territorial birds. Adult males attacked conspecifics at the same rate whether they had adult of female-like plumage (juvenile males and females) which does not support the winter adaptation hypothesis of the delayed plumage maturation in this species (cf. Rohwer & Butcher 1988). Robins defended winter territories against conspecifics, Black Redstarts and Stonechats (Saxicola torquata). Only two behaviors (territorial and non-territorial birds) were recorded. The attack rate against intruders was significant higher 1) on conspecifics, 2) early in the season, 3) when the temperature of previous days had been colder and 4) when the number of intruders per session was lower. Territories did not seem to be the best feeding areas since body condition and feeding intake rate did not differ between owners and floaters. However, owners spent a higher percentage of time hidden and were able to forage in less exposed areas (i.e. closer to shelter) than floaters, suggesting an anti-predation function of territories.

    These results suggest that site fidelity, familiarity with the winter area and the anti-predation behavior are important factors affecting the distribution, social organization, territoriality and presumably, winter survival of migrant birds in the Mediterranean area