Utility of arsenic-treated bird skins for DNA extraction

Background: Natural history museums receive a rapidly growing number of requests for tissue samples from preserved specimens for DNA-based studies. Traditionally, dried vertebrate specimens were treated with arsenic because of its toxicity and insect-repellent effect. Arsenic has negative effects on in vivo DNA repair enzymes and consequently may inhibit PCR performance. In bird collections, foot pad samples are often requested since the feet were not regularly treated with arsenic and because they are assumed to provide substantial amounts of DNA. However, the actual influence of arsenic on DNA analyses has never been tested. Findings: PCR success of both foot pad and body skin samples was significantly lower in arsenic-treated samples. In general, foot pads performed better than body skin samples. Moreover, PCR success depends on collection date in which younger samples yielded better results. While the addition of arsenic solution to the PCR mixture had a clear negative effect on PCR performance after the threshold of 5.4 μg/μl, such high doses of arsenic are highly unlikely to occur in dried zoological specimens. Conclusions: While lower PCR success in older samples might be due to age effects and/or DNA damage through arsenic treatment, our results show no inhibiting effect on DNA polymerase. We assume that DNA degradation proceeds more rapidly in thin tissue layers with low cell numbers that are susceptible to external abiotic influences. In contrast, in thicker parts of a specimen, such as foot pads, the outermost horny skin may act as an additional barrier. Since foot pads often performed better than body skin samples, the intention to preserve morphologically important structures of a specimen still conflicts with the aim to obtain optimal PCR success. Thus, body skin samples from recently collected specimens should be considered as alternative sources of DNA

The Predatory Ecology of Deinonychus and the Origin of Flapping in Birds

Most non-avian theropod dinosaurs are characterized by fearsome serrated teeth and sharp recurved claws. Interpretation of theropod predatory ecology is typically based on functional morphological analysis of these and other physical features. The notorious hypertrophied ‘killing claw’ on pedal digit (D) II of the maniraptoran theropod Deinonychus (Paraves: Dromaeosauridae) is hypothesized to have been a predatory adaptation for slashing or climbing, leading to the suggestion that Deinonychus and other dromaeosaurids were cursorial predators specialized for actively attacking and killing prey several times larger than themselves. However, this hypothesis is problematic as extant animals that possess similarly hypertrophied claws do not use them to slash or climb up prey. Here we offer an alternative interpretation: that the hypertrophied D-II claw of dromaeosaurids was functionally analogous to the enlarged talon also found on D-II of extant Accipitridae (hawks and eagles; one family of the birds commonly known as “raptors”). Here, the talon is used to maintain grip on prey of subequal body size to the predator, while the victim is pinned down by the body weight of the raptor and dismembered by the beak. The foot of Deinonychus exhibits morphology consistent with a grasping function, supportive of the prey immobilisation behavior model. Opposite morphological trends within Deinonychosauria (Dromaeosauridae + Troodontidae) are indicative of ecological separation. Placed in context of avian evolution, the grasping foot of Deinonychus and other terrestrial predatory paravians is hypothesized to have been an exaptation for the grasping foot of arboreal perching birds. Here we also describe “stability flapping”, a novel behaviour executed for positioning and stability during the initial stages of prey immobilisation, which may have been pivotal to the evolution of the flapping stroke. These findings overhaul our perception of predatory dinosaurs and highlight the role of exaptation in the evolution of novel structures and behaviours

Fungal enzyme sets for plant polysaccharide degradation

Enzymatic degradation of plant polysaccharides has many industrial applications, such as within the paper, food, and feed industry and for sustainable production of fuels and chemicals. Cellulose, hemicelluloses, and pectins are the main components of plant cell wall polysaccharides. These polysaccharides are often tightly packed, contain many different sugar residues, and are branched with a diversity of structures. To enable efficient degradation of these polysaccharides, fungi produce an extensive set of carbohydrate-active enzymes. The variety of the enzyme set differs between fungi and often corresponds to the requirements of its habitat. Carbohydrate-active enzymes can be organized in different families based on the amino acid sequence of the structurally related catalytic modules. Fungal enzymes involved in plant polysaccharide degradation are assigned to at least 35 glycoside hydrolase families, three carbohydrate esterase families and six polysaccharide lyase families. This mini-review will discuss the enzymes needed for complete degradation of plant polysaccharides and will give an overview of the latest developments concerning fungal carbohydrate-active enzymes and their corresponding families

Habitat effects on the breeding performance of three forest-dwelling hawks

PLoS ONE 10(9): e0137877Habitat loss causes population declines, but the mechanisms are rarely known. In the European Boreal Zone, loss of old forest due to intensive forestry is suspected to cause declines in forest-dwelling raptors by reducing their breeding performance. We studied the boreal breeding habitat and habitat-associated breeding performance of the northern goshawk (Accipiter gentilis), common buzzard (Buteo buteo) and European honey buzzard (Pernis apivorus). We combined long-term Finnish bird-of-prey data with multi-source national forest inventory data at various distances (100–4000 m) around the hawk nests. We found that breeding success of the goshawk was best explained by the habitat within a 2000-m radius around the nests; breeding was more successful with increasing proportions of old spruce forest and water, and decreasing proportions of young thinning forest. None of the habitat variables affected significantly the breeding success of the common buzzard or the honey buzzard, or the brood size of any of the species. The amount of old spruce forest decreased both around goshawk and common buzzard nests and throughout southern Finland in 1992–2010. In contrast, the area of young forest increased in southern Finland but not around hawk nests. We emphasize the importance of studying habitats at several spatial and temporal scales to determine the relevant species-specific scale and to detect environmental changes. Further effort is needed to reconcile the socioeconomic and ecological functions of forests and habitat requirements of old forest specialists.Peer reviewe

A possible new subspecies of the Philippine Hawk-Eagle (Spizaetus philippensis) and its future prospects

Volume: 32Start Page: 126End Page: 13

Hard times in the city - Attractive nest sites but insufficient food supply lead to low reproduction rates in a bird of prey

INTRODUCTION: Urbanization is a global phenomenon that is encroaching on natural habitats and decreasing biodiversity, although it is creating new habitats for some species. The Eurasian kestrel (Falco tinnunculus) is frequently associated with urbanized landscapes but it is unclear what lies behind the high densities of kestrels in the urban environment. RESULTS: Occupied nest sites in the city of Vienna, Austria were investigated along a gradient of urbanization (percentage of land covered by buildings or used by traffic). Field surveys determined the abundance of potential prey (birds and rodents) and the results were compared to the birds’ diets. A number of breeding parameters were recorded over the course of three years. The majority of kestrels breed in semi-natural cavities in historic buildings. Nearest neighbour distances (NND) were smallest and reproductive success lowest in the city centre. Abundance of potential prey was not found to relate to the degree of urbanization but there was a significant shift in the birds’ diets from a heavy reliance on rodents in the outskirts of the city to feeding more on small birds in the centre. The use of urban habitats was associated with higher nest failure, partly associated with predation and nest desertion, and with significantly lower hatching rates and smaller fledged broods. CONCLUSIONS: High breeding densities in urban habitats do not necessarily correlate with high habitat quality. The high density of kestrel nests in the city centre is probably due to the ready availability of breeding cavities. Highly urbanized areas in Vienna are associated with unexpected costs for the city dwelling-raptor, in terms both of prey availability and of reproductive success. The kestrel appears to be exploiting the urban environment but given the poor reproductive performance of urban kestrels it is likely that the species is falling into an ecological trap

Investigating the influence of local weather conditions and alternative prey composition on the breeding performance of urban Eurasian Kestrels <i>Falco tinnunculus</i>

<p><b>Capsule:</b> Local weather conditions, but not a city-associated diet composition, influence the breeding performance of urban Eurasian Kestrels <i>Falco tinnunculus</i>.</p> <p><b>Aims:</b> We aim to explore the impact of diet composition, specifically a high proportion of avian prey, on the breeding performance of urban Eurasian Kestrels under different weather conditions.</p> <p><b>Methods:</b> The Eurasian Kestrel is known to exploit cities and occurs in the study area of Vienna, Austria (415 km²) at high breeding densities of 89–122 pairs/100 km². Unlike their rural conspecifics which specialize in voles, urban Kestrels are generalists, preying on passerines and mammals, but also reptiles and insects. We explore this alternative diet through pellet analyses along an urbanization gradient over a 5-year period and link diet to reproductive performance, taking local weather conditions into account.</p> <p><b>Results:</b> Our results showed that weather had a greater influence on breeding performance than did diet. Warm and dry weather during the arrival and courtship period was correlated with earlier egg-laying, higher nestling survival and an overall higher breeding success. Dry winters increased the proportion of mammalian prey, whereas low temperatures and high rainfall during the nestling phase increased the proportion of avian prey. Overall, a more diverse diet was also associated with higher rainfall, but only during the arrival and courtship period.</p> <p><b>Conclusion</b>: Our research shows a stronger connection between breeding performance and weather conditions than between breeding performance and diet composition, although there may be indirect effects of weather on prey availability which augment the impact of diet on reproductive output in the Eurasian Kestrel.</p

Data from: Evidence of large-scale range shift in the distribution of a Palaearctic migrant in Africa

Aim: Long-distance Palaearctic migrant birds are declining at a faster rate than short-distance migrant or resident species. This is often attributed to changes on their non-breeding grounds and along their migratory routes. The European Honey-buzzard (Pernis apivorus) is a scarce migrant in southern Africa that is declining globally. This study assessed the distribution and abundance of honey-buzzards in southern Africa over the past four decades and compared it to trends in the East African population to examine possible drivers of population expansion in southern Africa. Location Southern and East Africa Methods European Honey-buzzard reporting data were collected from a variety of sources including citizen science databases (1983-2017). In addition, records of all other southern African vagrants (including ten other regularly occurring species) were gathered to account for changes in birdwatching effort in the sub-region. To assess the effect of forest loss on honey-buzzard abundance, rolling correlations were performed using forest cover in East Africa and number of honey-buzzard records in both sub-regions. Results European Honey-buzzard records in southern Africa have increased over five times more than other regularly occurring vagrant species and almost 40 times more than honey-buzzard in Tanzania, where the population has remained stable. Loss of forested area in East Africa was correlated with an increase in European Honey-buzzard records in southern Africa. Main conclusions We suggest that the European Honey-buzzard shift in wintering range may be driven by a decline in suitable habitat further north in Africa amongst other possible reasons. This effect may have been amplified by an increase in appropriate habitat across southern Africa brought about by anthropogenic changes to vegetation such as increased tree cover in urban areas. This study further highlights the importance of using African distributional data banks to understand the effects of global change on Palaearctic migrant bird species

The avifauna of Mt. Kitanglad, Bukidnon Province, Mindanao, Philippines

Intensive inventory work on the Mt. Kitanglad massif of north-central Mindanao, Bukidnon Province, Republic of the Philippines, revealed a diverse avifauna. In all, 198 bird species were detected, of which about 172 were likely breeding in the area, placing the mountain among the most diverse sites that have been surveyed in the country. Three migratory species (Luscinia calliope, Turdus chrysolaus, and Motacilla alba) were detected on the island for the first time by contributors to this summary, and known ranges of several species were extended. The massif holds populations of at least 17 of the 18 species narrowly endemic to Mindanao—more than any other site yet studied—as well as almost half the species endemic to the entire Philippine archipelago. Endemic species are concentrated at higher elevations, whereas migrants and widespread species are more frequent in the lowlands. The Kitanglad massif, however, has been modified severely below about 1200 m, with removal of almost all lowland forest habitats. Records and data accumulated by historical collectors, recent collectors, and recent observers are compared and contrasted to reflect on the biases, strengths, and omissions in each. The importance of the Kitanglad region to effective conservation of biodiversity in the southern Philippines is particularly emphasized