Dimitrios E. Bakaloudis

Population Estimates for the Diverse Raptor Assemblage of Dadia National Park, Greece

Summary. Population estimates for the diverse raptor assemblage of Dadia National Park, Greece. Dadia National Park, which is situated in north-eastern Greece, close to the border with Bulgaria and Turkey, is characterised by one of the most diverse arrays of breeding raptorial species in Europe. The first raptor survey was undertaken in the 1970s, but until 1999 most surveys were circumstantial and nonsystematic. Considering some of these species are globally endangered and included in Annex 1 of the Birds Directive, and that raptors in general are considered key indicators of biodiversity and ecosystem health, a systematic raptor monitoring programme was established by WWF Greece in 2000. This paper presents the results of this programme including the population status, trends and breeding densities of raptors from 2001 to 2005. Some 18–19 species bred in the area regularly, at densities ranging from one pair per 100 km2 (e.g. long-legged buzzard Buteo rufïnus and peregrine falcon Falco peregrinus) to 30 pairs per 100 km2 (common buzzard Buteo buteo). The total number of raptor territories was stable with an average of 321 ± 15.5 territories (77 territories/100 km2) with no overall trend and little fluctuation. Although the population size has increased for several species since the mid 1990s, data from the first surveys in the 1970s suggest that some species are still recovering from the decline suffered in the 1980s. The populations of six species have remained stable since the 1970s, whilst five species, including the Egyptian vulture Neophron percnopterus, have shown a gradual decline. The black vulture Aegypius monachus was the only species with a confirmed increase, a further three species showing a probable increase. The long-term trend for four species, including the common buzzard, is unknown due to insufficient data from the 1970s.

Aerial Hunting Behaviour of the Lesser Kestrel Falco naumanni During the Breeding Season in Thessaly (Greece)

Abstract. We studied the foraging behaviour of Lesser Kestrels in agricultural habitats during the breeding season of 2000. The birds spent more time hunting in flight than perched. During 398 min. of observed aerial hunting, they spent 23.7% hovering, 14.4% hanging, 14.0% flapping, 41.2% gliding, and 6.7% soaring. The time spent on each type of aerial hunting behaviour depended on factors like breeding stage, time of day, wind speed, number of strikes, number of successful strikes, and the time spent hunting. The strike rate was 0.38 per min., the capture rate 0.10 per min. The capture rate depended on the type of hunting behaviour preceding the attack and was highest after the birds had been hovering.

Diet Composition and Feeding Strategies of the Stone Marten (Martes foina) in a Typical Mediterranean Ecosystem

Stone martens (Martes foina) are documented as generalist throughout their distributional range whose diet composition is affected by food availability. We tested if this occurs and what feeding strategies it follows in a typical Mediterranean ecosystem in Central Greece by analysing contents from 106 stomachs, seasonally collected from three different habitats during 2003–2006. Seasonal variation in diet and feeding strategies was evident and linked to seasonal nutritional requirements, but possibly imposed by strong interference competition and intraguild predation. Fleshy fruits and arthropods predominated in the diet, but also mammals and birds were frequently consumed. An overall low dietary niche breadth (B A = 0.128) indicated a fruit specialization tendency. A generalised diet occurred in spring with high individual specialisation, whereas more animal-type prey was consumed than fruits. A population specialization towards fruits was indicated during summer and autumn, whereas insects were consumed occasionally by males. In those seasons it switched to more clumped food types such as fruits and insects. In winter it selectively exploited both adult and larvae insects and partially fruits overwinter on plants. The tendency to consume particular prey items seasonally reflected both the population specialist behaviour and the individual flexibility preyed on different food resources.

Key factors determining the seasonal population growth rate of European wild rabbits and their implications for management

Recently, the European rabbit (Oryctolagus cuniculus) has received contrasting considerations due to its multidimensional role in the Mediterranean ecosystems. Within this framework, knowledge of factors determining its population size may have important consequences for designing an effective management plan. In this paper, we quantified the combined influence of the major demographic and mechanistic factors on seasonal population fluctuation of European rabbits on Lemnos Island (Greece), during 2007–2009. We developed a hypothetical model taking into account direct (productivity, predation, hunting pressure, food shortage, habitat treatment) and indirect factors (soil moisture, adverse weather conditions) using structural equation modeling. We tested for their influence on the seasonal population growth rate (spgr) as determined by line transects to estimate rabbit abundance. The productivity induced higher pgr. Food shortage, which is affected by low soil moisture during the late summer and early autumn, is demonstrated to be the most important negative factor followed by the hunting pressure and predation. Demographic and mechanistic factors highlighted in this analysis could be used either for conservation or for controlling populations of the species.

Genomic evidence of demographic fluctuations and lack of genetic structure across flyways in a long distance migrant, the European turtle dove

BackgroundUnderstanding how past climatic oscillations have affected organismic evolution will help predict the impact that current climate change has on living organisms. The European turtle dove, Streptopelia turtur, is a warm-temperature adapted species and a long distance migrant that uses multiple flyways to move between Europe and Africa. Despite being abundant, it is categorized as vulnerable because of a long-term demographic decline. We studied the demographic history and population genetic structure of the European turtle dove using genomic data and mitochondrial DNA sequences from individuals sampled across Europe, and performing paleoclimatic niche modelling simulations.ResultsOverall our data suggest that this species is panmictic across Europe, and is not genetically structured across flyways. We found the genetic signatures of demographic fluctuations, inferring an effective population size (Ne) expansion that occurred between the late Pleistocene and early Holocene, followed by a decrease in the Ne that started between the mid Holocene and the present. Our niche modelling analyses suggest that the variations in the Ne are coincident with recent changes in the availability of suitable habitat.ConclusionsWe argue that the European turtle dove is prone to undergo demographic fluctuations, a trait that makes it sensitive to anthropogenic impacts, especially when its numbers are decreasing. Also, considering the lack of genetic structure, we suggest all populations across Europe are equally relevant for conservation.

Body condition variation of wild rabbit population in the north-east Mediterranean island of Lemnos — Greece

Abstract. European wild rabbit (Oryctolagus cuniculus) is a widely distributed species with a multiple role in both environmental sustainability and local economy. In the current study we examine the body condition of the species in relation to habitat type, age, sex and seasonality on the island of Lemnos. Body condition was assessed based on a visual estimation of the amount of abdominal fat. A high intra-annual variation in the body condition of the species has been observed, which is further affected by sex and age. The species appears to conserve and maintain high levels of energy reserves for two main reasons. The first is to ensure a better reproductive success, as expressed by the relatively high amount of stored fat reserves at the onset of breeding season, and their depletion during it. The second is to ensure survival during periods where the shortage of food creates a rather hostile environment, as expressed by the increased level of reserves during summer and their dramatic decrease from late summer until autumn. The temporal fluctuation in energy reserves differs between male and female rabbits, reflecting their temporally different energy demands. Further, differences in body conditions were observed between juvenile and adult individuals, reflecting their different needs in terms of body growth and maintenance. Our results could offer important insights for the development of a time specific management plan and measures to ensure either the control of the population or its conservation.

The influence of habitat structure on the European brown hare Lepus europaeus food habits in mountainous areas of northern Greece

No abstract available

Home range and foraging habitat selection by breeding lesser kestrels (Falco naumanni) in Greece

Home range size and foraging habitat use in breeding lesser kestrels (Falco naumanni), a bird species of conservation concern, were investigated during the breeding season of the species in 2008 in an intensively cultivated area of central Greece, using radio-tracking. Grasshopper (the main prey) densities were measured at the most important habitats (cotton, cereals, grasslands and margins). Home ranges were not significantly different between sexes either as overall means or during incubation and nestling periods. Movements of both sexes were non-random during incubation but random during the nestling period. Habitats used by males during incubation ranked as: margins > other > cotton > corn > cereals and during nestling period as: cereals > margins > grasslands > corn > cotton. Female habitat use greatly differed ranking as cereals > cotton > grasslands during incubation and as grassland > cotton > corn > cereals > margins during nestling period. Female habitat use seemed to be in disagreement with the conditions generally favouring prey availability, probably for reasons associated with low and uniform distribution of grasshopper densities over the habitats.

Trophic ecology of the European wild rabbit Oryctolagus cuniculus on the Mediterranean island of Lemnos, Greece

The European wild rabbit (Oryctolagus cuniculus) is a species with a wide distribution across the globe and a contradicting role in the ecological integrity of ecosystems and local economies. Despite the considerable amount of research that has been conducted on the trophic ecology of the species in continental environments, similar studies in insular environments are still fairly scarce. The article examines the trophic ecology of wild rabbit, using microhistological analysis to study its annual dietary composition in relation to the availability and quality of food sources, in two different habitats of a northeast Mediterranean island. A total of 112 species were found to participate, to a lower or greater degree, in the species diet across the year. The available food sources, as well as the identified food items, were classified in three feeding functional groups (FFGs), namely, grasses, forbs and parts of woody plants. Wild rabbit follows a diverse diet having adapted to the seasonal changes in the availability and quality of food sources. Forbs is the FFG which constitutes the main food source of the species, while grasses and parts of woody plants form occasionally an important component of its diet. The FFG of grasses is almost constantly preferred in both habitat types and plays a deterministic role in the trophic ecology of wild rabbit. During the critical dry season, where the availability of high quality food becomes limited, the species preferably consumes taxa that are generally less palatable and even toxic in its struggle for survival.

Impact of European wild rabbits foraging in different habitat and vegetation types in an insular environment

Abstract European wild rabbits (Oryctolagus cuniculus) are prolific herbivores, affecting natural and agricultural ecosystems. We installed 10 experimental units, each consisting of two fenced plots, one excluding all herbivores and one allowing rabbit access only, to estimate the impact of rabbit grazing in three vegetation types occurring in two dominant habitat types on Lemnos Island, Greece. Plant productivity was significantly higher in barley crops than on both fallow land and Mediterranean scrublands. Rabbit grazing caused significant reduction of productivity in barley crops and Mediterranean scrublands, but not on fallow land. Selective feeding and seasonal food availability may have shaped patterns of rabbit impact.