The Common Buzzard is a partial migrant in Eastern Europe, but its wintering densities are poorly known for this area due to a low number of studies. However, its migration patterns and wintering grounds can be affected by climate change with local fluctuations in numbers linked to weather conditions. Between 2010 and 2015 we annually carried out 15 transects/winter month in order to count the wintering population of Common Buzzards across Eastern Romania to look for climatic factors explaining variation in wintering density. Transects were controlled during two weeks from the end of the month, each covering a distance of 40 km, outlining the broadest winter monitoring of raptors in Central and Eastern Europe. Road survey was used, with a car driving at a low speed, and two observers counting birds, recording distance and habitat where birds occurred. In analyses, in addition to local weather data also 9 indices integrating weather conditions across longer time windows and larger areas were included. The wintering density calculated for the five-year period was 0.539 individuals/km² fluctuating during the winter seasons with a possible cyclic pattern. The Buzzards selected pastures and herbaceous vegetation associations for hunting across their wintering grounds. Common Buzzard numbers fluctuate during the winter season (highest in December). They are positively influenced by rising solar flux and negatively by the low North Eastern Europe temperatures and Arctic Oscillation Index recorded within 14 days before the survey, which drive birds to southern wintering areas. These weather conditions (high pressure and low temperatures) represent the onset of the Siberian Anticyclone, a regular, annual weather system that occurs in Eastern Europe every winter.

Recent climate warming has resulted in advancement in laying dates and changes in various bird breeding parameters. The study of the breeding biology of Great Reed Warblers Acrocephalus arundinaceus was carried out at Milicz fishponds (SW Poland) during 18 discontinuous breeding seasons between 1970 and 2017. Over the study period, Great Reed Warblers started breeding progressively earlier; both the earliest and median first egg laying dates advanced, whereas the latest laying dates remained unchanged. Egg volume and clutch size did not change between 1972 and 2017. Mean clutch size of all nesting attempts was 4.8 (SD = 0.69, n = 1135). Nestling growth rates were similar in 1971 and 2016. Nestling period shortened during the study period. The decrease amounted to 0.7 days between 1970–1984 and 2004–2017. No temporal trends in fledgling production were observed. The proportion of successful broods varied considerably between years (range: 37%−76%) but did not show any consistent trend throughout the study period. More cases of Cuckoo Cuculus canorus parasitism were observed in 1997−2017 than in 1970−1984 (7% of nest losses versus 0 respectively), whereas starvation of nestlings was more frequent in 1970−1984 (10% versus 2% of nest losses). Breeding densities varied between seasons with no significant trend across the study years. This study concludes that the advanced start of breeding has not significantly influenced basic parameters of breeding ecology of the Great Reed Warbler.

In numerous and extensive studies on birds in cities, woodpeckers have usually been neglected. Most research has only considered their suburban populations. Among European woodpeckers, only the Syrian Woodpecker Dendrocopos syriacus is synanthropic, occupying both rural and urban areas. In this study, habitat requirements of sympatric Syrian and Great Spotted D. majorWoodpeckers were investigated in two urban populations from central Poland. The occurrence of Syrian Woodpecker was found to be associated with walnut trees, fruit trees and mainly older softwood trees (poplars, willows). Plots with Syrian Woodpeckers were characterized by trees scattered among single-family buildings and within tenement houses in town centres. In contrast, plots with Great Spotted Woodpeckers were densely wooded, often with high share of hardwood trees and located in suburbs or residential woods. The aforementioned results show that these two sibling woodpeckers occupy different niches in urban populations. Moreover, this study supports the statement that urban areas are important for the Syrian Woodpecker in central Europe — a rare species in the European Union. Trees removal in cities, especially softwood trees, is a serious threat to the preservation of Syrian Woodpecker populations.

Translocation is a useful tool for the conservation of endangered species, because it enables individuals to be moved between wild populations and between captivity and the wild. The use of captive-raised animals in these processes is sometimes the only option to recover a declining population, but captive-raised parrots are commonly seen as the worst candidates for release because they lose their ability to recognize predators, to find food in the wild and to socialize with conspecifics. The Blue-fronted Amazon Amazona aestiva is one of the most popular parrot species in captivity. Thirty-one parrots were soft released and monitored during 13 continuous months in a Cerrado area (savannahlike vegetation) of Minas Gerais State, southeastern Brazil. Three released parrots (10%) were confirmed to die and five (16%) disappeared soon after release and no behavioral recordings or data about their destinations were available. Ten parrots (32%) showed behaviors that suggest adaptation to the wild and 13 individuals (42%) expressed behaviors more typical of captivity. Difficulties in settling were observed for the parrots after release. One released pair, and one female paired with a wild male, reproduced. There was a tendency to decrease in all captive-related behaviors and to increase in wild-related behaviors since time after release. Supplementary food use diminished as the parrots explored natural food resources. This study indicates that confiscated captive-raised parrots can be good candidates for translocation if a training program could be applied prior to their release to reduce undesirable behaviors and the chance of re-capturing by humans. Furthermore, the use of non-endangered species in conservation programs can be useful to create protocols for the conservation programs of rare and endangered species.

We studied the sequential use of tree cavities by the cavity-nesting bird community in a riparian forest ecosystem of south-western India during 2013–2015. During the study period, a total of 376 nests of 20 cavity-nesting bird species comprising six primary and 14 secondary cavity nesters were located in the riparian forest. The cavity use pattern showed that one-third of the cavities were reused by birds and that the majority of the reused cavities were located in live trees. A lesser proportion (5%) of cavities used by birds was reused by other animal taxa. Competition for nest cavity use was observed among bird species in which Common Myna Acridotheres tristis was found to be the major competitor. A strong correlation was found between the bird body mass and nest cavity dimensions. Cluster analysis based on tree and cavity characteristics divided the avian community into five groups. We constructed a nest web for community structure that showed cavity resource use by various primary and secondary cavity-nesters. Woodpeckers (Greater Golden-backed Woodpecker Chrysocolaptes guttacristatus, White-naped Woodpecker C. festivus, and Browncapped Pygmy Woodpecker Dendrocopos nanus) as well as barbets (Brown-headed Barbet Psilopogon zeylanica, Coppersmith Barbet P. haemacephala and White-cheeked Barbet P. viridis) formed the key excavators in the riparian forest. While many of the smaller secondary cavity-nesting birds depend on the excavated cavities for nesting and reproduction, large-sized birds used decay formed cavities.

Recent climate change is frequently invoked as the cause of changes in phenology and distances of migration. Birds are expected to reduce the length of migration in response to milder climatic conditions, and during the last years, there are a growing number of records of European long-distance migrants wintering in the Iberian Peninsula. For this reason, we have used in this study the available ringing and recoveries data for the Eurasian Reed Warbler in the Iberian Peninsula during winter, spanning 1959–2015. We show that during the last decades this insectivorous species occurs regularly during winter in South-western Europe, which could be related to the recent climate change. Some Iberian birds wintered in breeding areas, or nearby, which could indicate a potential process of sedentarization, while Eurasian Reed Warblers from Central and Northern Europe shortened the migration distance avoiding the crossing to Africa. Iberian wintering grounds seemed to be related to the origin of the birds, with British Eurasian Reed Warblers staying more northerly that individuals from Central Europe, and Eastern birds showing a tendency to winter on the Mediterranean coast. Our results support the contemporary trend of migrants overwintering at higher latitudes. Despite the considerable increase of wintering records during the last decades, we cannot confirm a real expansion because there has been an increase in ringing activity over the study period. Nevertheless, the presence of this species has become consistent during winter in well-sampled areas where it was absent in the past. With warmer winters we expect changes in the migratory system, and also an increase in frequency of long-distance migrants that avoid the crossing of the Mediterranean and the Sahara desert to remain in southern Europe during cold months.

Woodpeckers are important primary excavators that produce nest-sites that are also used by several other cavity-nesting animals. However, the value of nest sites produced by different woodpecker species for other cavity-nesters is not generally known. We studied old Three-toed Woodpecker Picoides tridactylus cavities to examine their importance for other cavity-nesting forest bird species. Over a 31-year period (1987–2017), we annually monitored the occupancy of 655 cavities excavated by the Three-toed Woodpecker in 86 territories of the species in a 170-km² area in southern Finland. Eight bird species used old Three-toed Woodpecker cavities for breeding, and the occupancy of these cavities by all secondary users was 21.3%. The expected mean number of lifetime occupancies by secondary cavity-nesters for a single cavity was 2.03. This is equivalent to a mean of two cavities occupied per territory per year, if we assume that Three-toed Woodpeckers produce a new cavity every year. The actual numbers of annually occupied cavities by secondary cavity-nesters can be substantially lower especially in territories that are not constantly occupied by the Threetoed Woodpecker. Based on the use of old cavities and densities of secondary cavity-nesting bird species, we conclude that cavities made by Three-toed Woodpeckers are most significant for the species itself, which accounted for 23.3% of nests in old Three-toed Woodpecker cavities. When Three-toed Woodpeckers reused an old cavity rather than occupy a freshly excavated cavity, 93% of cavities selected were originally excavated by Three-toed Woodpeckers. In addition, old cavities are important for the Pygmy Owl Glaucidium passerinum — up to 26–31% of breeding attempts were in old Three-toed Woodpecker cavities. The importance of old cavities for other hole-nesting bird species like the Pied Flycatcher Ficedula hypoleuca or the Great Tit Parus major was rather minor considering their densities within woodpecker territories.

The Greater Rhea Rhea americana is a South-American flightless bird whose populations have decreased due to poaching and fragmentation of suitable habitats, and there has been an urgent need to carry out management practices to prevent local or regional extinctions. Several studies revealed that reintroduction might be an appropriate action for increasing the viability of wild populations of this species. Nevertheless, although this is a popular and useful conservation strategy, the animals to be released should be prepared against risks like predation and dispersion that could influence the post-release success. We evaluated the effect of an antipredator training applied to captive-bred Greater Rheas before they were released into the wild, on their dispersal and home range size and overlap, supposing that the trained animals would avoid dispersing into places with predators and, consequently, they would reduce their home range. We also studied the habitat use by the released rheas. Eleven trained and nine control (untrained) animals were marked and monitored two to four times per day during the first week, and from 4 to 19 consecutive days per month during four months, throughout the breeding and post-breeding seasons. The antipredator training affected the home range in different ways according to sex. Trained females exhibited smaller home ranges (mean ± S.E.: 0.54 ± 0.58 km²) than the rest of the individuals (control females 5.8 ± 0.75 km², control and trained males: 2.11 ± 0.65 km² and 2.96 ± 0.65 km², respectively), whereas their overlap was greater (63.83 ± 16.95%) than that of the untrained females (24.04 ± 21.88%). Males of both experimental groups showed similar distances travelled (3.21 ± 0.29 km), which were also greater than those of females (2.21 ± 0.32 km). The home ranges of males were not influenced by the training and they showed a high degree of overlapping (among control males 29.96 ± 18.95%, and among trained males: 35.81 ± 18.95%). Both groups similarly used crops and in lesser extent open areas and grassland. Only the trained females reduced their movements and wandering as a result of the previous conditioning. They moved to crop or open areas, avoiding tall vegetation such as that present in grasslands, which may make difficult to detect predators. On the other hand, in the males, the influence of the reproductive season and the complex mating system exhibited by this species prevailed over the possible effects of training. Our work shows new and useful data about the spatial behaviour and reintroduction for conservation of the Greater Rhea.

Bird nests are variable in design but all are constructed for the purpose of incubation. The potentially onerous energetic costs of incubation have meant that previous studies have focussed on thermal insulation but nests are often exposed to a variety of environmental factors, including rainfall. Those few studies that have investigated the effects of water on nests have saturated the walls by soaking but this may not reflect what a nest would typically encounter in situ during rainfall. Here, nests of four species of songbird (Common Chaffinch Fringilla coelebs, Common Linnets Linaria cannabina, Meadow Pipits Anthus pratensis, and Whinchats Saxicola rubetra) were investigated using temperature loggers to determine the effect of simulated rainfall on nest wall insulation. Simulated rainfall, produced by water dripping through a coffee percolator, significantly reduced the insulatory values of nests, and significantly increased the rate of cooling of temperature loggers inside the nest cup. No significant effect of species, or nest mass, was observed. Even when wet nest walls provided some insulation but whether this is attributable to the nest materials chosen by each species was not clear. The nest site chosen by the birds may also offer considerable protection from the weather. Further research is needed to better understand how rainfall affects the insulative properties of nests in situ.