Birds, Volume 5, Issue 3 (September 2024) – 12 articles

Single individuals of the Greater Spotted Eagle (Clanga clanga), Indian Spotted Eagle (Clanga hastata), Tawny Eagle (Aquila rapax), Western Marsh Harrier (Circus aeruginosus), and two Pallid Harriers (Circus macrourus) were deployed with satellite transmitters in 2021 to study their home ranges, habitat associations, movement, and migration patterns. Data were collected for a combined number of 2291 days, providing 84,544 locations. Home ranges were calculated as kernel utilization distributions and expressed as 95% KDE and core areas as 50% KDE. Overall, eagles had larger home ranges (mean ± SD) of 942.70 ± 937.83 km² compared to harriers, 43.84 ± 35.55 km². Among eagles, the Greater Spotted Eagle had the largest home-range size of 2147.03 km² calculated in Kazakhstan, while the female Pallid Harrier had the smallest home range of 5.74 km² in Russia. Daily and monthly distances varied among eagles and harriers. The female Pallid Harrier covered the longest average monthly distance of 8585.43 ± 11,943.39 km, while the shortest monthly distance of 1338.22 ± 716.38 km was traveled by the Indian Spotted Eagle. All tagged birds migrated toward higher latitudes in the Northern hemisphere, except the Indian Spotted Eagle, which migrated to Pakistan. The male Western Marsh Harrier covered the longest migration distance in a shorter span of time, while the female Pallid Harrier took the longest to cover its migration distance. Overall, the daily distance covered during migration varied from 115.09 km traveled by the Indian Spotted Eagle to an overwhelming distance of 2035.85 km covered by the male Western Marsh Harrier. Scrubs, water bodies, croplands, and settlements were important habitat features associated with eagles, while croplands, open scrub, and built-up areas were associated with the female Pallid Harrier. The male Western Marsh Harrier was found to be primarily associated with saltpans and salt-affected areas having emergent vegetation. This study presents new insights into the movement and spatial ecology of long-distance migrant raptors that winter in Western India. We provide preliminary support for the use of the Western Circum–Himalayan Corridor as one of the important corridors of the Central Asian Flyway that warrants much appreciation among the current set of flyway corridors. Full article

Despite high-quality insect food being often restricted in cities, insects are important for the development of birds. Nonetheless, plenty of insects are smashed on cars, and they are available for those species that are able to use them. We used both our own data and community science and Internet sources for surveying global, national, and local data about birds using insects on cars. Our results contained a total of 308 observations of birds collecting insects on car panels, which indicated that 39 species used this food resource since 1928 in 33 countries. Most observations considered the House Sparrow, followed by the White Wagtail and several species of corvids. European urban bird species observed to use insects on cars had a larger residual brain size. There was also some indication that bird species using insects on cars had a larger number of innovations (i.e., production of novel behaviors), greater diet generalism, and longer times living in urbanized areas than birds not observed using insects on cars. Often these species are also resident and able to use food offered in feeding sites. We assume that more bird species will use insects on cars in the future, as urban insect populations continue to decline, and thereby insects on cars will increasingly become more important sources of food for urban birds. Full article

In the Galapagos Islands, the main road in Santa Cruz is one of the elements involved in bird road mortality along with vehicles and the impacted species. This study reports the number of roadkilled birds found on the road from the Itabaca Channel to Puerto Ayora, and the main factors, whether avian or environmental, involved in bird roadkill mortality. We collected individual carcasses in 2004, 2005, 2006, and 2018 with a prevalence of 278, 252, 265, and 294, respectively, across 21 species. The endemic Yellow Warbler Setophaga petechia aureola was the most affected bird. We used a PRIDIT model to rank the top avian and environmental predictors of road mortality. We found that for the sampled years, bird body size (i.e., 8–35 g) and the endemism status (i.e., endemic/native) were the main predictors of roadkill mortality, along with seasonality (i.e., hot season). Weaker predictors related to the bird (i.e., age and sex) and the environment (ecosystem, road slope, vegetation, or precipitation) are also reported as determinants of roadkill mortality. This study on avian mortality aims to inform conservation strategies to reduce the rate of wildlife avian roadkill on Santa Cruz Island and other islands with similar problems. Full article

Abandoned mine drainage treatment ponds could have contrasting effects on the reproductive success of birds living in the vicinity. The ponds and associated vegetation may, like any other body of freshwater, provide beneficial habitats for the insects that the birds use to feed their young; or instead, the ponds may act as an ecological trap, attracting the birds to a habitat that is poor in quality and negatively impacting their productivity. We monitored nests of an aerial insectivore, the Tree Swallow (Tachycineta bicolor), to determine whether the distance between the ponds and the nests affected various reproductive parameters including clutch size, hatch rate, number of nestlings, nestling size and mass, number of fledglings, fledging rate, and fledge date. Data were collected over two breeding seasons (2022 and 2023) from a swallow population in southwestern Pennsylvania, USA. We found that the nests closest to the treatment ponds had significantly more nestlings and fledglings, earlier fledge dates, and a better fledging rate when compared to nests that were more distant from the ponds. However, all these parameters were well below previously published values, which suggests that the mine drainage ponds provide good nesting habitats relative to what is available in the region but that they do not represent high-quality habitats for this species overall. Full article

Raptors (Accipitriformes, Falconiformes and Strigiformes) are important for ecological niches as bioindicators and an apex predator; however, their global populations have continuously decreased due to human activities, habitat loss and contagious diseases. Avian malaria that may cause the negative impact on raptors’ health may also contribute to the declining of raptor populations. This study reported malaria’s molecular prevalence and genetic diversity in wild-caught and rehabilitated raptors in the Kasetsart University Raptor Rehabilitation Unit. In total, 109 raptors from 18 provinces of Thailand were classified into two groups, which included 78 diurnal raptors (DIRs) in Accipitriformes and 31 nocturnal raptors (NORs) in Strigiformes. Each ethylenediaminetetraacetic (EDTA) blood sample (0.5–1 mL) was tested through haematological analyses and polymerase chain reaction (PCR)-based detection to assess parasites’ health impacts. Amplicons of PCR positive samples were analysed for a nucleotide sequencing and phylogenetic relationships. The overall prevalence of avian malaria was low at 3.67% (4/109) (95% CI: 1.44–9.06%), with a prevalence of 3.86% (3/78) (95% CI: 1.32–10.70%) in DIRs and 3.23% (1/31) (95% CI: 1.32–10.70%) in NORs. Most of the infected samples were from southern Thailand. This suggested that the raptors in humid habitats are more vulnerable to the malarial infection, which was likely associated with vector and parasite abundance. Clinical appearances and haematological examinations demonstrated that raptors could tolerate the infection and only became asymptomatic and subclinically infected. This study is the first report of the infection of avian malaria in Cinerous Vulture, Himalayan Vulture and Barred Eagle Owl in Thailand, providing baseline information in preparedness for the disease diagnostic and further study of avian malaria in some endangered raptor species. Full article

Psittacine beak and feather disease virus (BFDV) is a widespread and highly pathogenic virus in parrots. The disease typically presents with feather and beak abnormalities, along with possible immune system suppression. No cure or commercialized vaccine is currently available. Our understanding of the Psittacine beak and feather disease often comes from infected individuals with visible symptoms. Limited knowledge exists regarding the pathology and role of asymptomatic individuals in disease transmission. Asymptomatic individuals could shed the virus in their crop secretion, feces, or feathers. In this study, we investigated the temporal change in the viral load in feather and fecal samples from 17 asymptomatic Rosy-faced Lovebirds (Agapornis roseicollis) using qPCR. Our results showed that most of the individuals had very low viral load, while three individuals with high viral load at the beginning of the experiment were observed to exhibit a decreasing trend in viral load in both fecal and feather samples. Surprisingly, the viral load in an individual can drop from a high level to an undetectable level within three months. This suggests that BFDV infection might not be lethal or highly pathogenic for some individuals. We also showed that the viral load in feathers was higher than in feces. Full article

Grasslands are one of the most threatened terrestrial biomes leading to a loss of grassland biodiversity, including birds. Here, we studied the wintering grassland bird diversity and community structure in two private livestock ranches in the Chihuahuan Desert, Mexico. We explored how bird communities are related to vegetation structure, including shrub cover and invasive exotic natal grass (Melinis repens), two drivers of grassland bird habitat degradation. We used Hill’s numbers to estimate taxonomic species richness and diversity and related these metrics to vegetation covariables using linear models. We employed nonmetric dimensional scaling (NMDS) to explore the importance of vegetation covariates in structuring bird communities. We found that bird species diversity was significantly and negatively related to bare ground cover at a plot level. At the ranch level, shrub cover, grass height and natal grass were important in structuring avian communities, negatively affecting the presence and abundance of grassland specialist bird species. Our results indicated that shrub encroachment and invasive exotic natal grass cover may alter grassland bird communities and should, therefore, be considered in grassland bird conservation management. Full article

As tropical forests are frequently impacted by human disturbance, forests in various stages of disturbance recovery are increasingly important for maintaining biodiversity. However, much remains unclear regarding the impacts of prior disturbance intensity on wildlife in regenerating forests. Here, we used mist net capture data to compare bird communities in three tropical forest habitats representing various disturbance intensities: undisturbed primary forest, selectively logged forest (low disturbance), and secondary forest regenerating on abandoned agricultural fields (high disturbance). We found that after a 19-year recovery period, low-disturbance sites contained similar bird communities to undisturbed sites. High-disturbance sites, however, had lower species richness and distinct bird communities, with fewer insectivores and more nectarivores than other sites. Structural equation models revealed that the impacts of disturbance intensity on bird communities were partially explained by changes in vegetation structure: ant-following insectivore abundance declined with disturbance intensity as ground cover vegetation increased, and nectarivore abundance increased with disturbance intensity as tree density decreased. Our results suggest that selectively logged forests can regain pre-disturbance bird diversity and vegetation structure within two decades, provided that they are protected from further disturbance and located near source species pools. Increasing tree density and decreasing ground-level vegetation in secondary forests may improve these areas as habitats for forest-interior birds. Full article

Synanthropic birds might play an important role as reservoirs of many zoonotic endoparasites; however, little information is available on many parasites and their prevalence. Here, we use an approach based on targeted metagenomic detection through the use of DNA metabarcoding of faecal samples to screen for circulating parasites in alien parakeets (Myiopsitta monachus and Psittacula krameri) and urban landfill-feeding storks (Ciconia ciconia) and gulls (Larus fuscus). We focus especially on potentially zoonotic parasites, with the aim of better understanding the zoonotic risk that these birds’ faeces may pose. We detected a total of 23 genera of eukaryotic parasites: six fungi, three protists, five nematodes, two cestodes and seven trematodes. Among them, six stood out for their relevance to human health: Cryptococcus spp., Aspergillus spp. and Candida spp. (fungi); Cryptosporidium spp. (a protist); and Ascaris spp. and Halicephalobus spp. (nematodes). In parakeets, we detected Cryptococcus spp. and Ascaris spp., the latter being detected in 10–20% of the samples. In the White Stork and the Lesser Black-backed Gull, we found a high prevalence of Aspergillus spp. (in 15% and 50% of the samples, respectively) and Candida spp. (in 63% and 82% of the samples, respectively), and the presence of Cryptosporidium spp. in 10% of the samples. We detected Halicephalobus spp. in one gull sample (2%). Our results show that synanthropic birds may act as vectors and reservoirs of zoonotic parasites and their faeces could pose a risk to human health associated with the zoonotic parasites present in them. This should be taken into account when developing management plans for urban populations of these bird species. Full article

Wildlife value orientations (WVOs) are useful for gaining knowledge about how humans’ relationship to nature, wildlife, and management differs between groups in society. Our study investigated the level of acceptance for the implementation of measures to avoid the disturbance of golden eagles among hikers with different WVOs. Our results indicated differences between WVO typologies regarding how they assessed the consequences of outdoor recreation on nature and wildlife, as well as measures to manage human traffic. These findings contributed to confirming our hypotheses that peoples’ WVOs have an impact on how people assess wildlife and the natural environment, and that WVOs affect the acceptance of management measures. This study concluded that identifying and studying visitors’ WVOs contributes to understanding the underlying dimensions that influence peoples’ attitudes and behavior. WVOs has not been studied in a Norwegian context previously, and this study contributes new knowledge that is useful for managing human–wildlife relations in more sustainable ways. Full article

Short-wavelength artificial light at night is increasingly being associated with health and ecological risks. The negative impact of this relatively new source of pollution has been studied intensively in wild birds but to a much lesser extent in captive conspecifics. Using an avian model, our objective was to evaluate the effects of short-wavelength (200 lux at 460 nm) lighting on the body mass and reproductive success of Budgerigars (Melopsittacus undulatus) under captive conditions. Birds were maintained under a naturally increasing photoperiod from March to June, with one daily artificial light at night exposure of increasing duration (0, 30, 60, and 90 min) in the middle of the dark period. During the experiments, birds were monitored monthly for body mass, number of eggs laid, hatching success, and melatonin sulfate levels in droppings. Artificial light at night increased body mass and decreased melatonin sulfate levels as well as the number of eggs and hatching success in a duration dose-dependent manner. Our findings provide further evidence of the potential adverse impact of artificial light at night on captive birds and advocate the need for effective controlling measures for light pollution. Full article

We compared Snowy Owl feeding ecology from 15 breeding season studies throughout Nearctic and Palearctic circumpolar regions. We used raw data and information theory to assess the owls’ feeding niche. Combined studies yielded 59,923 prey items, of which 59,585 were used for calculations. Overall, mean food niche breadth (FNB) was narrow: H′ = 1.95; R = 1.60, D = 0.526. In 10 of 15 studies, lemmings were > 71.8% of the owls’ diet. In four studies, Lemmus was > 90% of the diet, and in three studies Dicrostonyx was >90% of the diet. In three other studies, Lemmus represented 71.8%, 73.8%, and 84.0% of the diet. In one study, Lemmus and Dicrostonyx were about equal: 49.1% and 47.5%. In the four remaining studies, Microtus and Clethrionomys voles were important. In contrast, of 5888 winter prey items from seven North American studies, the mean FNB (H′ = 4.61) was twice that of 15 breeding season scores, FNB (H’ = 1.95). The Snowy Owl is primarily an obligate lemming predator for breeding. Changes to population ecology and distribution of lemmings due to climate change will have direct affects and effects on the Snowy Owls’ reproductive output. The conservation of Snowy Owls is the conservation of lemmings. Full article