Status and structure of the griffon vulture (Gyps fulvus) population in Crete

Abstract

Griffon vulture (Gyps fulvus) population surveys were conducted during 1996-2002 in the island of Crete (Greece) to document population status and structure. Fieldwork was carried out during the breeding period when birds could be monitored in their colonies. Total population size was estimated at 379 individuals (range = 341-417) with adult birds comprising 63%. The breeding population was estimated at 141 pairs, which were distributed on an average in 23 colonies per year (range = 16-30) while the mean number of breeding pairs that laid eggs was 98 (range= 64-126). Crete thus supports the largest insular population of the species in the world and hosts 70-80% of the breeding population of the species in Greece. Population density was estimated at 6.9 individuals/100 km 2 , 2.6 breeding pairs/100 km 2 and 1.8 nesting pairs/100 km 2 . The average home range of an occupied colony (i.e., breeding group) was estimated at ca. 204 km 2 producing a theoretical foraging range of 8 km radius around the breeding cliff. No trends in the total number of individuals and breeding pairs appeared to exist, although significant differences in population size of individual colonies occurred between the years. The majority of the population was concentrated in small-sized colonies, which showed a low occupancy rate. The number of abandoned sites and the colonization of new ones could represent a shift of breeding pairs to alternative colonies provoked by local food abundance and conspesific attraction.

Foraging Behaviour and Flight Characteristics of Eurasian Griffons Gyps fulvus in the Island of Crete, Greece

“…More specifically, the mean nearest neighbour-colony distance was 17 km (range : 13.8-23.6) which is considerably larger than the mean of 10.3 km for the island (Xirouchakis & Mylonas 2004). The mean number of individuals and egg-laying pairs per colony was 23¡5 (range : 14-28) and 6¡4 (range : 1-9), respectively, which were larger than the island means of 14¡0.9 individuals and 3.7¡0.6 egg-laying pairs per colony (Xirouchakis & Mylonas 2005). Nests and roosts were situated on vertical limestone cliffs at an altitude that ranged from 200-550 m. Mean values for the period 1990(Region of Crete 2000 showed that all study colonies annually received 760-1260 mm of precipitation.…”

“…Crete (8,261 km 2 ) holds the largest insular griffon population worldwide numbering ca 140 breeding pairs concentrated in 23 nesting colonies (Xirouchakis & Mylonas 2005). The species represents a characteristic case of long standing cohabitation with man as it has depended on livestock (i.e.…”

Selection of Breeding Cliffs by Griffon VulturesGyps fulvusin Crete (Greece)

“…At present, according to the Greek Red Data Book, the species is considered as endangered (Handrinos 1992) with the island of Crete harboring the most significant subpopulation in the country (i.e. 141 breeding pairs, Xirouchakis & Mylonas 2005). This fact has been attributed to the low use of poisoned baits for vermin and the existence of suitable foraging and nesting habitat.…”

Long‐term griffon vulture population dynamics at Gamla Nature Reserve

“…The factors influencing the observed decline are numerous and similar in many countries within the species’ distribution range (Bahat , Terrasse et al , Xirouchakis and Mylonas , Choresh , Buechley and Şekercioğlu ). An important case was recorded in the Indian subcontinent where the cause of the decline of 3 vulture species (Prakash , Gilbert et al , Prakash et al , Green et al ) was established beyond any doubt (Oaks et al ).…”

“…Second, we observed fluctuations in the vultures counted, with lower numbers in spring and higher numbers in autumn and winter; this is characteristic to the species, as seen in other countries (Xirouchakis 2007, Boshoff et al 2009), regardless of the threatening decline. The factors influencing the observed decline are numerous and similar in many countries within the species' distribution range (Bahat 1997, Terrasse et al 2004, Xirouchakis and Mylonas 2005, Choresh 2011, Buechley and S Sekercio glu 2016). An important case was recorded in the Indian subcontinent where the cause of the decline of 3 vulture species (Prakash 1999, Gilbert et al 2002, Prakash et al 2003, Green et al 2004) was established beyond any doubt (Oaks et al 2004).…”