Christos G. Vlachos

Nest spacing and breeding performance in Short- toed Eagle Circaetus gallicus in northeast Greece

Capsule There is some evidence of susceptibility to stochastic or human factors. Aims To describe the phenology and breeding success of one of the densest populations of Short-toed Eagle in Europe. Methods All nests in the Dadia–Lefkimi–Soufli forest in northeast Greece were located and visited regularly throughout the 1996–98 breeding seasons. Data on every stage of the breeding cycle were collected and related to among-year variation in the weather conditions during March to June. Results A total of 58 pairs were located during the three-year study spread across 22 territories (the same territories are usually occupied each year). The nests were evenly spaced (mean of 2.7 km between nests). Adults arrived between mid-March and mid-April. Only one egg per nest was laid. Nestlings fledged on average after 68.9 days. Eagles departed between 8 September and 2 October. Conclusions Arrival date determines laying date. The population size appears to be stable but the species has a relatively low reproductive rate and takes three to four years to mature, consequently it may be susceptible to stochastic or human-mediated factors.

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.

Population trends of Black Vulture Aegypius monachus in Dadia Forest, north-eastern Greece following the establishment of a feeding station

Dadia Forest in north-eastern Greece is well known for its diversity of breeding birds of prey. In 1980, the area was declared a wildlife reserve. One of the most endangered species at that time was the Black Vulture Aegypius monachus. To help the population of Black Vultures a feeding station was established in 1987. A monitoring programme from 1984 until present indicates that the operation of the feeding station has coincided with an increase in the numbers of Black Vultures wintering in Dadia by nearly threefold, an increase in the number of breeding pairs from 10 to 21, and an increase in breeding success from 40% to a peak of 95%. A slight faltering in the continued rise in the numbers of Black Vultures in Dadia is attributed to a poisoning event in 1995.

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.

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.

Evaluating the Potential of Three-Dimensional Laser Surface Scanning as an Alternative Method of Obtaining Morphometric Data

External anatomical measurements have a long tradition in morphometric studies. Recently, three-dimensional laser surface scanners have revolutionized the way such measurements can be obtained. The aim of this study was to quantify measurement error (hereafter ME) and reliability of several linear skull measurements of the red fox obtained with three different techniques: using calipers, and by analyzing two- and three-dimensional digital images. Differences between observers had the highest ME values for most traits, followed by method and replicate. Inter-observer variability contributed the most to total ME. Measurements obtained from calipers and two-dimensional digital images showed high agreement, validating their use in traditional morphometric studies. The laser surface scanner was unreliable when compared with the reference in almost half the traits. To achieve greater accuracy, in future studies full advantage of the devices capabilities should be taken. Objects should be scanned in high definition, from many angles and orientations, and self-calibration should be performed.

Patterns of postnatal growth in a small falcon, the lesser kestrel Falco naumanni (Fleischer, 1818) (Aves: Falconidae)

Abstract Following a dramatic decline, the lesser kestrel Falco naumanni global population has recently stabilised, although it is still fluctuating in several countries, including Greece. Nestling growth rates and size at fledging greatly influence future survival and reproductive success, and therefore the study of postnatal growth can aid the understanding of population dynamics and the conservation of avian populations. We quantified body mass and morphological traits in female and male lesser kestrel nestlings from a lowland Greek breeding population. Nonlinear mixed models were used to describe and compare growth trajectories. Growth in body mass, tarsus and bill reached asymptotic values before fledging and was best described by the logistic equation, whereas total length grew linearly beyond the fledging phase. Random variation was found in the asymptote in body mass, the inflection point in body mass, tarsus and bill lengths and the intercept in total length, being substantially higher between nests than amongst siblings, implying differences in parental quality between nests and also an even distribution of parental care amongst siblings. Random effects were not observed on the growth rate constant, supporting the hypothesis that it varies little within populations. Females were significantly heavier and had longer bills and total length than males, whereas males were similar to females in tarsus growth. Nonlinear mixed models allowed us to describe a stage of avian life vital for future survival and reproductive output and reveal variation between nests, nestlings and the sexes.

Assessment of Nestling Diet and Provisioning Rate by Two Methods in the Lesser Kestrel Falco naumanni

Abstract. Nowadays the use of remote photography systems is very popular for diet assessment. Despite the popularity, there is a greater need for evaluation of these systems against traditional methods of diet assessment, such as direct visual observation. The diet of Lesser Kestrel nestlings and adult provisioning rate were assessed using cameras and direct observations at four nests with various brood sizes during the breeding season in 2013. The study was conducted in an intensively cultivated area that belongs to a Special Protected Area of the Natura 2000 network in central Greece. Diet composition (prey type and size) was not affected by the recording method, the sex of adults, the brood size, the period of the day or the age of nestlings. Tettigoniidae was the most frequent prey delivered by adults. Our results from both methods showed that males delivered more prey items than females, supporting the general consensus of reversed sexual dimorphism for the Lesser Kestrel. The provisioning rate was not significantly related to brood size, but it was affected by the method of observation, parent sex and the interaction of method and nestling age. According to the direct observations, provisioning rates increased as nestlings grew up, while they decreased based on camera information. Higher provisioning rates recorded in direct observations at later nestling stages, can be explained by higher food requirements of nestlings. The decrease in provisioning rate with nestling age was mostly affected by the camera function, as a result of digital limitations, nest type and Lesser Kestrels behavior.