Avian Biology Research

A flightless female Eagle Owl Bubo bubo has survived for one year with food provided by its partner. The pair bred successfully and raised one owlet in 2015. The favourable combination of characteristics on the rocky slope nest site occupied by the pair provided the female different escape routes from potential enemies, natural protection of the nest and access to water during the time of laying, incubation period and hot summer weather. Voles (Microtus sp.) were the most numerous prey (55.8% by number, 15.3% by biomass) because of their population spike during the period with a flightless female in the pair. Rats (Rattus sp.; 16.2% by number, 31.2% by biomass), a key prey resource, also increased to a level several times greater than in previous years. The significant differences in diet during 2015 did not appear to cause any obvious changes in Eagle Owl breeding characteristics at the site. The increasing prey on voles and rats created the narrowest food niche and reduced food stress according to the rather lower value of superpredation (3.6% by number, 9.9% by biomass).

Urbanisation has profound impacts on birds via, for example, changes in activity budgets, distributions and movements influenced by resource availability, and the connectedness of preferred habitats. We live in an urbanising world and yet understand little about how urbanisation affects the basic biology of organisms that share urban spaces with us. A case in point is nest construction and nest maintenance behaviours that require significant investments of time and energy by birds early in the breeding attempt. Here, we studied how position on an urban gradient in the city of Birmingham, UK, influenced the composition and ectoparasite load of nests of Blue Tits (Cyanistes caeruleus). In total, we deconstructed 131 nests removed from nestboxes at the end of the breeding season in 2014 at 30 different locations along an urban gradient. Nest composition varied significantly along this gradient with significant relationships between feather content and built cover (negative), and connected tree cover (positive). Notably, anthropogenic materials were found in 73% of nests but their inclusion was unrelated to position on the urban gradient. The only identifiable ectoparasites in nests were Siphonapterans (fleas) and although ectoparasite load was unrelated to position on the urban gradient, it was positively related to nest mass. Taken together, we show that even for a common species that is often referred to as an ‘urban adapter’, the urban gradient influences nest composition and ectoparasite load, and thus potentially reproductive outcomes of small passerines. The challenge is to roll out this approach over multiple years to test the applicability of our findings over longer timeframes and their broader implications for a wide range of bird species that are routinely found breeding in increasingly urbanised landscapes globally.

Avian coccidios, caused by Eimeria, has been shown to cause weight loss and bloody diarrhoea, and sometimes even death of chicks, which subsequently has a serious negative impact on the development of the poultry industry. Berberine is a Chinese traditional medicine for intestinal disorders, which has been shown to have preventive effects on intestinal epithelium that has been exposed to external damage. In the present study, anticoccidial activity of berberine was tested in vivo using Eimeria tenella, on its effects on daily weight gain, bloody diarrhoea, oocyst production, thickness and lesions of caecum. The data confirmed that infected chicks with Eimeria tenella started to show classic clinical symptoms on day 4–5 post-infection, such as ruffled feathers, bloody diarrhoea and reduced weight gain. There was significant reduction in oocyst production of berberine treated chicks except those infected by oocysts pretreated with berberine. The caecum epithelia thickness and lesions were significantly higher in the infected/untreated chicks than those in uninfected/untreated and infected/treated chicks. The results of this study indicate that continuous prophylactic treatment with berberine significantly improved the pathogenic conditions. It is concluded, that berberine is likely to work through preventing caecum epithelium barrier damage from Eimeria tenella by suppressing the reproduction of Eimeria tenella and restoring the normal functions of chicks’ caecum.

Our aim was to determine the ophthalmic parameters and describe the eye histology of Blue-and-yellow Macaws (Ara ararauna) and Lear's Macaws (Anodorhynchus leari) kept at the Triage Center for Wild Animals (CETAS) and in Getulio Vargas Zoobotanic Park (Salvador, northeastern Brazil), respectively. Thirty four clinically healthy macaws (28 Blue-and-yellow Macaws and six Lear's Macaws) were studied. The investigation included culture of the conjunctival bacterial flora, evaluation of tear production by endodontic absorbent paper point tear test (EAPPTT) and phenol red thread test (PRTT), measurement of palpebral fissure length (PFL), corneal touch threshold (CTT) and intraocular pressure (IOP), as well as characterisation of conjunctival cytology samples, B-mode ultrasonography, and eye histology of one Blue-and-yellow Macaw. There was a predominance of Gram-positive bacteria in the samples analysed and the microorganism colonies were resistant to tetracycline and oxacillin. Blue-and-yellow Macaws had significantly higher EAPPTT than Lear's Macaws, but there were no differences in PFL and IOP. Conjunctival cytology revealed predominance of squamous and columnar epithelial cells. The pecten, a pleated structure located on the optic nerve and projecting into the vitreous, was composed of several large blood vessels and capillaries. The ophthalmic parameters determined in this study may help in the diagnosis of ocular diseases in Blue-and-yellow and Lear's Macaws.

Melatonin receptors are G-protein coupled receptors which mediate the action of melatonin hormone. In this study, we investigated the effects of two different lighting systems, 23 h L: 1 h D (group I) and 12 h L: 12 h D (group II), on reproductive traits in Japanese Quail (Coturnix coturnix japonica). As well as the expression pattern of three melatonin receptor subtypes, mRNA in ovaries and testes were analysed using quantitative real time PCR. The results revealed the expression of all three subtypes of melatonin receptors (MNTR1A, MNTR1B and MNTR1C) in ovaries and MNTR1B, MNTR1C in testes in both groups. Further, the expression of melatonin receptors was significantly higher in group II relative to group I. The fold change level of MNTR1C was 6.7 in ovaries and 3.1 in testes in short day light. Altered expression pattern of these genes associated with changes in Japanese Quail reproductive traits, while, Japanese Quail exposed to long day light started egg laying earlier than those in short day light. Egg weight and egg percentage increased significantly in group I compared to group II. The average of relative ovary and testis weight at six weeks of age were declined by 1.72 and 1.64 g, respectively, in group II. It was concluded that, different lighting system induced different expression levels of melatonin receptor genes accompanied with changes in reproductive traits in both sex of Japanese Quail.

There is a dearth of published data related to, or describing, the detailed anatomy and histology of the avian gut from oesophagus to cloaca, apart from that relating to commercial poultry. Without an accepted description of normal anatomy it is difficult for researchers to know whether observations in a specific population are normal or not, or for veterinarians to know what to expect during surgery or necropsy, and impedes the understanding of the remarkable adaptations among or within species. Also, as interest in the physiological role played by gut microbiota increases in avian studies, knowledge of species-specific gastrointestinal anatomy is essential. European Starlings (Sturnus vulgaris) are a prolific, well-studied invasive species across much of the world, and yet there is no information describing the anatomy of the gastrointestinal tract, or how it compares to similar species. Here, we describe the anatomy, histology and histochemistry of gastrointestinal tracts from 15 day old starlings from the proximal oesophagus to distal cloaca in order to facilitate comparison among species and different populations of the same species.

Climate conditions may determine the foraging strategy of migratory birds at spring stopovers. For geese, this period is a crucial time for acquiring energy to fuel onward migration and ensure future breeding success. Our study, analysing the influence of weather factors on numbers of geese and foraging sites, was conducted in the Biebrza Basin (northeastern Poland) during the spring migration period in 2007–2013, when a total of 116 counts were carried out. A total of 741,865 White-fronted Geese and 20,871 Greylag Geese were counted. Numbers of geese differed among habitat types; Greylag Geese used arable lands more frequently than White-fronted Geese, which in turn preferred grasslands. Two climate factors affected numbers of the latter: the impact of mean 10-day temperature was positive but that of snowfall was negative. Neither of these factors affected the former. We conclude that changeable climate conditions in the temperate climatic zone may force a more flexible response in terms of habitat use during stopovers from short-distance migrants like Greylag Geese than from longer-distance migrants like White-fronted Geese.

Natural environments have been altered by many human actions and during the last decades this process has been hastened in an alarming way. In the Pampean and Espinal ecoregions of Argentina, agriculture was the major contributor, producing a homogeneous landscape of cultivated lands interrupted by few small, isolated pieces of natural environment or noncultivated lands. We studied bird assemblages in two types of agricultural landscapes, one with crops located within a heterogeneous landscape matrix, such that crops were bordered by different types of noncultivated environments, and the other with crops located within a homogeneous landscape matrix away from noncultivated areas. The main objective was to compare the bird assemblage structure and composition between these two landscapes to test the hypothesis that heterogeneous agricultural landscapes support greater bird diversity than do homogeneous landscapes. We recorded 33% of the total abundance in the crops within a homogeneous matrix (CHOM) and 67% of the total abundance in the crops within a heterogeneous matrix (CHEM). The CHEM points had greater species richness, and composition of species differed between CHOM and CHEM. Thus, the results support the hypothesis that environmental heterogeneity increases bird diversity in agricultural areas, with important consequences for ecosystem services that biodiversity provides to agricultural ecosystems and for the conservation value of these systems. The fact that the protected areas by themselves are not sufficient to guarantee biodiversity conservation emphasises the important role that areas under cultivation can play. Our data provides evidence that the presence of uncultivated environments can increase the importance of agricultural lands for biodiversity conservation and, at the same time, can benefit agroecosystems by supporting bird species that can function as biological control agents of agricultural pests.

Data obtained from wildlife rescue centres are a useful means of understanding threats posed to wild animal populations. Aims of the present study were to investigate the causes of admission and outcomes of Long-eared Owls (Asio otus) hospitalised in rescue centres in Italy. Data were collected from 13 centres form January 2010 to October 2014 using a web form. The following variables were considered: estimated age at admission; date of admission; habitat at finding location; main cause of admission; and outcome. Major causes of admissions were related to human activities, mainly consisting of collision trauma and collection of uninjured fledglings. Despite nocturnal habits of owls and their protection status, according to European Union Directive 2009/147/ CE and to national Italian laws, gunshot wounds were also represented as an admission cause in adult animals. Overall mortality rate was 47.3%. Considering age classes, the majority of adult animals died while the majority of pulli survived and were later released. Both collisions and gunshot wounds contributed to the higher mortality in adult animals. We suggest that anatomopathological and toxicological investigation of dead casualties, along with post release monitoring of rehabilitated owls, would contribute to a better understanding of mortality causes and to the implementation of more successful rehabilitation techniques.