Physiological functions of growing nestlings are thought to be traded-off in relation to rearing conditions, with the resulting physiological state of fledglings having important long-lasting consequences for their fitness. By manipulating brood size up and down, and, separately, by supplying additional food (mealworms — larvae of Tenebrio molitor) we tested if alterations of the rearing conditions would influence nestling performance in Blue Tits Cyanistes caeruleus and Great Tits Parus major. Brood size manipulation affected body mass, heterophil-to-lymphocyte ratio (H:L) and fledging probability in both species and the level of triglycerides in nestling Great Tits. Extra food supply influenced only fledging probability, with no other effect on indicators of nestling performance. An effect on nestling body mass and a lack of effect on cell-mediated immune response in the brood-size experiment suggest that nestlings in enlarged broods sacrificed growth to maintain immunity. In general, effects of both types of experiments were probably to some extent masked by specific character of the study site — an urban parkland with high human-induced disturbance.

Species with known long-term changes in abundance and distribution enable exploring the role of newly accessible sites in population regulation. In Western Europe, the Black-tailed Godwit Limosa limosa islandica is one of the few wintering shorebirds with increasing populations. The French coasts comprise a major wintering site within its global wintering area, with several thousand individuals at some sites. Nevertheless, the role and importance of French sites in general distribution patterns of the species remain unclear, especially as its hunting was legal there until 2008. In contrast, recent increases in protected areas in France (from 4,000 ha in 1973 to 28,000 ha in 2005) offer new safe sites and suitable habitats for the species. In this study, we assessed the numbers and distribution of Black-tailed Godwits along the coasts of Western France. The main wintering sites in France are progressively occupied from August, reaching peak occupation in late autumn or early winter although few of the ten sites listed showed similar patterns of monthly variations in the distribution of Godwit numbers. France welcomes c. 28% of the total L. l. islandica population in mid-winter over the period 2003–2007. Numbers declined steadily from the base year (1977) until 1991, then progressively increased, reaching a maximum in 2010 (c. 27,000 individuals). The creation of Nature Reserves throughout the 1990s probably contributed to the increasing number of Godwits in France, with new accessible sites visited and occupied intensively during the period of population increase. The clearly contrasting phenologies between the British Isles and France suggest that most of the individuals first arrive in the United Kingdom after the breeding season, and then some of the birds move to southern sites in either France or Iberia, while very few birds fly directly to France from Iceland.

Migrating birds are known to avoid topographical barriers. At these barriers, the local environmental conditions often lead to a high concentration of migrants at certain corridors or points usually referred to as ‘bottlenecks’. The Greater Caucasus and the Caspian Sea are such barriers for migrating birds in south-western Asia. A narrow coastal plain between the Greater Caucasus and the Caspian Sea in Azerbaijan (Besh Barmag bottleneck) provides excellent conditions for studying bird migration of a poorly known region. Here, surveys were carried out in autumn 2011 and spring 2012 to count raptor, passerine and waterbird migration from three different observation points. Data for fixed block of six hours continual observations together with random counting hours have been interpolated by a special calculation to obtain estimated grand totals per species. In total, 278 bird species were recorded, eight of which are red-listed as globally threatened by the IUCN (i.e. Sociable Lapwing Vanellus gregarius, White-headed Duck Oxyura leucocephala, Saker Falcon Falco cherrug, Egyptian Vulture Neophron percnopterus, Lesser White-fronted Goose Anser erythropus, Dalmatian Pelican Pelecanus crispus, Eastern Imperial Eagle Aquila heliaca, Greater Spotted Eagle Aquila clanga), another eight as ‘near threatened’. Calculations indicated 1.24–1.51 million visible migrants in autumn 2011 and 0.65–0.82 million in spring 2012. For four species (Eurasian Skylark Alauda arvensis, Common Starling Sturnus vulgaris, Rosy Starling Sturnus roseus, Little Bustard Tetrax tetrax), the mean passage estimates exceeded 100,000 individuals. 15 species meet or are well within the range of the criterion of 1% of the world population. For a further 19 species they exceed the criterion of 1% of the flyway population. Dalmatian Pelican and Little Bustard were observed in great numbers representing 33–57% and 41–48% of the world population, respectively. Both species and, additionally, raptor and waterbird migration are discussed. The results presented here serve to underline the importance of Azerbaijan for migrating bird species in general, and to highlight in particular the great potential of the study area as a location for long-term monitoring studies in a remote and little-studied region.

Since the 1990s, Common Cranes migrating in autumn through Italy have increased significantly both in number and in flock size. In the present study we provided a countrywide profile of autumn crane migration across Italy between 2001 and 2007 (486 records). To investigate the association of climatic characteristics with temporal and spatial migration patterns, we used weather data and climate anomalies over 60 years (1948–2007; NCEP/NCAR Reanalysis Project database). Autumn migration showed different phenological patterns along two main migratory routes: 1) a Southern Italy route and 2) a Northern Italy route. The Southern route, across the lower Adriatic Sea was only partially described before, and more inferred than documented, whereas the Northern route, across the Po River plain, resulted as a new flyway, never described before. Crane migrations along the Northern route occurred 7 to 14 days earlier than along the Southern one. Along both routes, we detected mass migration events concurring with particular weather conditions: the use of Southern route was associated with southward winds in the Balkans, the records along Northern route with high pressure and favourable westward winds in Central Europe and in the main stop-over site (Hortobágy) of likely origin. In the last 60 years, the occurrence of the latter weather configurations has slightly, but consistently, increased, suggesting that the Northern route may have recently established as an alternative route for the cranes migrating from Eastern Europe, joining the two traditional continental routes (the West-European, and the Baltic-Hungarian).

Central parts of avian colonies provide better safety against predators and, thus, are likely to be occupied by pairs of high quality. Therefore, spatial variation in the quality of breeders and predation rate within colonies should be directly reflected by the gradients of breeding success and chick survival. We have investigated relationships between nest location characteristics and survival of Whiskered Tern Chlidonias hybrida chicks in the colony at Jeziorsko reservoir, central Poland. We found that pairs nesting in the central, densely occupied areas of subcolonies had higher chick survival rates in comparison to edge pairs. There was also strong support for the positive effect of egg size and the negative effect of hatching date on the chick survival. Since pairs breeding in the central parts of subcolonies laid eggs of greater size and initiated laying earlier, we suggest that within-colony patterns of chick survival could be primarily attributed to the spatial variation in parental quality rather than to the higher predation pressure in the peripheral zones of the colony. There was also a moderate support for age variation in the survival rates of chicks, which ranged from 0.72 ± 0.06 to 0.91 ± 0.07 in different 5-day intervals of pre-fledging period. The survival of chicks over the entire pre-fledging period was estimated at 0.29–0.33, depending on the model.

Breeding success determines the fate of bird populations and, therefore, understanding its determinants is an important issue for the application of conservation measures for endangered species. Breeding success depends on diverse, not mutually exclusive, effects such as the life strategies developed by species, environmental, ecological and anthropogenic factors. The influence of nest and nest tree characteristics, landscape composition and human disturbance on the breeding success of the vulnerable Cinereous Vulture Aegypius monachus in breeding colony in central Spain was analysed. A number of variables characterising the vegetation around the nest-tree, the nest-tree, and the nest itself were selected and analysed. We found that bigger and less deteriorated nests, taller nesting trees and a higher shrub coverage in a radius of 100 m around the nest resulted in an increased breeding success. Although nesting sites characteristics and nest quality can be related to birds' age and breeding experience, our findings show that geographical orientation of the slope where the nest is located as well as nest accessibility and habitat selection have an influence on Cinereous Vulture breeding success. We recommend that mature forests, steeper slopes should be carefully conserved and protected from anthropogenic disturbances in order to strengthen the conservation of breeding areas of this forest-dwelling endangered raptor species.

Parental investment is a key topic in avian ecology, and many authors have focused on nestling-feeding behaviour to analyse this issue. Surprisingly, most studies have based their results on feeding patterns recorded over periods of only one or two hours, possibly leading to over generalizations regarding temporal-dependent behavioural patterns. Irrespective of nestling age or brood size, if we use observations from such short periods as conclusive evidence we must assume that parents behave consistently across time and that the window of time selected is representative of parental effort. To test this assumption, we analysed the time consistency of nestling provisioning rates and prey composition of 32 breeding pairs of Mediterranean Great Tits Parus major, from dawn to midday (7 hours recording). Regardless of a parallel decrease in the intensity of work for both sexes, we found that hourly provisioning rates per nestling correlated strongly with the mean number of feedings per nestling and per hour recorded over the whole 7 hours of recording. Weather conditions and nestling age had no effect on hourly provisioning rates per nestling, although parents with older nestlings worked relatively less hard. We also observed that the peak of morning activity was higher in nests with small clutches. Prey proportions showed a high degree of temporal repeatability, but nestling diet composition should be studied with caution. Although prey composition was stable over time, we recorded a strong decrease in the number of prey items delivered by parents throughout the day, along with an increase in prey size. We thus recommend using a wider time window to obtain reliable results when studying prey composition. In any case, considering our results, one hour of recording may be sufficient to describe nestling-feeding behaviour of Great Tit parents.

In Europe, Dupont's Lark Chersophilus duponti is a threatened open-habitat bird. Prescribed burning has sometimes been proposed for its conservation, but without evidence of its effectiveness. To evaluate the short-term effects of a summer wildfire on this species, we performed several transect counts in the burnt and unburnt parts of a shrubsteppe in central Spain. The same transects were counted within a three-year interval prior to the fire and were repeated during the first two springs after the fire. We also measured the vegetation during the first two springs after the fire. In the burnt area, we observed a decrease of about 85–100% in Dupont's Lark abundance, and about 7–15% in the control area. The disappearance of the scrub cover after fire and its slow regeneration, as well as the large increase in grass cover during the second year, may explain the decrease in this habitat-specialist bird species. Fire should be avoided in areas occupied by the Dupont's Lark, as its negative effects in the short-term may cause local extinctions. However, prescribed burning may be used in neighboring areas to create new open habitats that may be subsequently colonized by this species.

The key demographic parameters of a population of Hyacinth Visorbearer, Augastes scutatus, an endemic hummingbird of the mountaintops of southeastern Brazil, are described for the first time. The study was conducted in the Alto do Palácio region, in the Serra do Cipó National Park, southeastern Brazil. Monthly, from August 2007 to July 2009, the Hyacinth Visorbearer individuals were captured in mist nets and banded. Using mark-recapture data, we modeled monthly apparent survival (φ;) and capture probability (p), with sex and time (month) as covariates. We considered two time-since-marking (TSM) models among candidate models to control for the possible effect of transient individuals on parameter estimates. The two best-supported models (gaining 74% of summed Akaike weight) included effects of transient birds on monthly survival, with constant capture probability. The model-averaged apparent survival estimates for the first month after capture (φ;¹) were considerably lower than the values for the second and later months following capture (φ;² ). The apparent monthly survival showed difference between sexes, with females' value (φ;² = 0.93 ± 0.03) slightly higher than males' value (φ;² = 0.90 ± 0.03). These differences translated into distinctly higher annual survival of females (0.418 ± 0.16) than males (0.318 ± 0.12). The estimated annual capture probability was high (75%). We strongly suggest that TSM effects should be evaluated in future humming bird population studies.

Cooperative breeding is not common among birds, although its frequency is relatively high within the Corvidae family. We study the effect of group breeding on the reproductive biology of the Carrion Crow Corvus corone, a species that was usually described as non-cooperative. Our study population is located at the southern limit of the distribution of the species, which confers special characteristics to its breeding biology. Early breeders had a significantly larger clutch size and produced a higher number of fledglings. Replacement clutches were very rare and always unsuccessful, contrary to what happens in other European Carrion Crow populations. More than half of the breeding attempts (66.1%) in our study area showed cooperative breeding but it had only a significant effect on laying date — group-breeding females laid eggs significantly earlier than did pair-breeding females. We also explored brood parasitism by Great Spotted Cuckoos Clamator glandarius on the reproductive success of Carrion Crows. Brood parasitism reduced the number of both hatched nestlings and fledglings. However, group-breeding and pair-breeding nests had similar probabilities of being parasitized. Finally, we also examined the effect of some meteorological variables on the breeding performance of Carrion Crows. The average precipitation during the nestling period was positively related with number of fledglings raised.

Dispersive behaviour in birds is shaped by a set of different external factors (climate, human pressure, territory quality), as well as by internal constraints (reproductive strategy, sex, age, competitive abilities). Natal and breeding dispersal was studied in the migratory population of the Mute Swan Cygnus olor in Poland. The species showed male-biased natal dispersal with mean dispersal distance of 99.7 ± 20.0 km for males and 17.7 ± 5.4 km for females. Consistently, larger proportion of female swans showed natal philopatry, when compared with males (36.4% vs. 9.1%). The dispersal distance has shortened over the last three decades. This tendency prevailed in males and was associated with reduction in annual migration distance due to milder winters and adaptation for wintering in urban areas. Analysis of breeding dispersal showed that only 12.3% of breeding attempts were associated with changing territories (N = 945). Breeding dispersal distance was female-biased (0.66 ± 0.19 km for females vs. 0.35 ± 0.14 for males; N = 316 individuals). Occurrence of mate-switching and poor reproductive success were positively associated with probability of dispersal, but moving to a new territory did not increase breeding output in a season following dispersal event. Dispersive behaviour in the Mute Swan may be perceived as a part of species-specific ecological flexibility, allowing individuals to adjust to the changing conditions at the breeding grounds.

In birds, offspring-parent interactions play an essential role in facilitating offspring survival at nest-leaving. In contrast to nidicolous nestlings, nidifugous chicks are expected to hatch in ground nests, leave the nest soon after hatching, and presumably exhibit precise parent-offspring recognition during this time. Yet, some studies document variation in nidifugous behavior and offspring-parent recognition of semi-precocial chicks during the nest-leaving stage in the family Laridae. We examine patterns in nest-leaving age, mobile capacity, and parent recognition in wild and captive chicks of the Saunders's Gull Saundersilarus saundersi that is one of ground nesting and colonially breeding species. Our results indicated that the development of locomotor activity in nidifugous chicks coincided with the nestleaving age. Soliciting behavior of experimental chicks increased with age, but they strongly discriminated vocalizations of pseudo-parents against unfamiliar adults only at the early stage of nest-leaving. We suggest that parent recognition by chicks during this short period may play a key role in facilitating their own survival while moving to a new environment with their parents after leaving the nest. More studies using a comparative approach are needed to understand how nesting ecology, nest-leaving behavior, and parent-offspring interaction are interconnected in the members of the family Laridae.

It is widely known that parents invest into reproduction to increase offspring survival and thereby increase reproductive success. In particular, female birds allocate maternal resources including lipids, hormones, and nutrients into the egg yolk. Carotenoid pigments, which are responsible for the characteristic yellow, orange, and red colours, are particularly important as antioxidant for the developing embryo. The Investment Hypothesis addresses variable female allocation of maternal resources into egg yolk and predicts that high quality females and females paired to high-quality males will invest more in their eggs. We test predictions of the Investment Hypothesis in the Diamond Firetail Stagonopleura guttata. In captive females and their pair males, we compare yolk carotenoid (lutein and zeaxanthin) allocation and egg size in relation to traits indicative of individual quality (body condition, flank spot number, bill and rump colour). Females with more white flank spots laid larger eggs that contained more lutein, the major carotenoid found in the Diamond Firetail eggs. Total carotenoid concentration in egg yolk was not related to any other female characteristic. Females laid larger eggs when paired with a high quality male (dark red rump).