Predator density influences nest attendance of Yellow‐headed Blackbirds Xanthocephalus xanthocephalus

Nest attendance behaviour in birds is a function of the careful balance between the risk of nest predation and the needs of the parents and nestlings. This attendance must be carefully regulated, as increased parental activity at the nest increases nest predation risk. We tested the long-standing hypothesis that nest predation risk influences parental behavior by evaluating the influence of local Marsh Wren Cistothorus palustris density on the off-bout frequency of Yellow-headed Blackbirds Xanthocephalus xanthocephalus. Marsh Wren density was negatively correlated with Yellow-headed Blackbird off-bout frequency during the morning (0500-1000), day (1000-1600), and evening (1600-2100), suggesting that Yellow-headed Blackbirds alter their nest attendance behaviour in response to a perceived increased risk of nest predation. We suggest that Yellow-headed Blackbirds are sensitive to nest predation risk and alter their behaviour accordingly to increase overall fitness, although future research is needed to evaluate the influence of Marsh Wren nest predation on the reproductive success of Yellowheaded Blackbirds

Patterns of predator behaviour and wood warbler Phylloscopus sibilatrix nest survival in a primaeval forest

Understanding the foraging behaviour of predators is key to interpreting the role of anti-predator adaptations of birds in reducing nest losses. Conducting research in primeval habitats, with low direct human interference, is particularly valuable in the understanding of predator-prey interactions. Using nest cameras, we investigated the identity and behaviour of potential and actual predators appearing at Wood Warbler Phylloscopus sibilatrix nests, and the importance of different predator groups for nest survival, in the primeval part of Białowieża Forest (Poland). Mammals formed the main predator group (30 of 32 nest depredations), particularly medium-sized carnivores (24 of 32), which attacked nests more frequently than merely passing by. This contrasted with other species, especially small rodents that were commonly recorded near nests but rarely attacked them. Most nest attacks (22 of 32) took place at night and nest survival did not depend on nest visibility, indicating a reduced utility of nest concealment in defence against predators using mainly sound or olfaction when hunting. Daily nest survival declined strongly with nest progression (from egg-laying to fledging of chicks), likely due to increased predator detection of nests containing older and louder chicks, and not due to increasing parental activity at nests during the day. The set of actual nest predators differed from some previous studies in human-transformed habitats, showing that Wood Warblers may face differing threats in modified versus near-pristine environments

Cameras, Coyotes, and the Assumption of Equal Detectability

Remote cameras are an increasingly important tool in management and wildlife studies. However, we often do not know if they provide an unbiased sample of populations. Using a marked, radio-collared population of coyotes (Canis latrans) of known social status, we evaluated the influence of temporal (daily and seasonal) and spatial (distance between units, habitat, and proximity to human structures) factors on vulnerability to photo-captures. During 8 unbaited camera sessions of 6 weeks each, we obtained 158 coyote photographs at a photo-capture success rate of 1.6%. We were able to identify not only marked individuals, but also a number of uncollared adults through variation in their pelage. Photo-capture of adults peaked 2 weeks after we established camera stations. Annual success for photographing adult coyotes was greatest during March and April, which corresponded with the dispersal season. The majority of photo-captures occurred at night, and adult photo-captures peaked around midnight, with smaller peaks at dawn and dusk. Rather than reflecting a circadian activity pattern, nighttime captures seemed to reflect when adult coyotes were most vulnerable to photo-capture. Characteristics of camera locations, such as amount of human activity, being on roads versus trails, and habitat type, also influenced the number of photo-captures. We conclude that remote cameras do not always provide an unbiased sample of populations and that animal behavior is important to consider when using these systems. Researchers using camera techniques need to carefully consider when, where, and how cameras are placed to reduce this bias

Dispersal: a matter of scale

Population density around the natal site is often invoked as an explanation for variation in dispersal distance, with the expectation that competition for limiting resources, coupled with increased intra‐specific aggression at high densities, should drive changes in dispersal distances. However, tests of the density‐dependent dispersal hypothesis in long‐lived vertebrates have yielded mixed results. Furthermore, conclusions from dispersal studies may depend on the spatial and temporal scales at which density and dispersal patterns are examined, yet multi‐scale studies of dispersal are rare. Here, we present the findings of a long‐term study examining factors influencing natal dispersal distances for the non‐migratory population of Peregrine Falcons (Falco peregrinus) in the British Isles across distinct spatial and temporal scales. Our smallest scale study included Peregrines ringed as nestlings and subsequently recaptured alive in south Scotland–north England, an area that was intensively studied during the time periods 1974–1982 and 2002–2016. Second, we examined dispersal patterns of birds ringed as nestlings in south Scotland–north England, but subsequently recaptured alive or recovered dead anywhere in the British Isles. Finally, we examined the natal dispersal patterns for Peregrines ringed and recaptured or recovered anywhere in the British Isles from 1964 to 2016. Consistent with prior findings, females dispersed farther than males across all scales. However, the patterns of dispersal were strongly scale dependent. Specifically, we found a lack of a discernible relationship between index of density and dispersal distance in the limited study area, but when region‐wide recaptures and recoveries were included in the analyses, a negative relationship was revealed. Our results suggest that conclusions of dispersal studies may be scale dependent, highlighting the importance of spatial and temporal scales in examining and interpreting the relationship between population density and dispersal patterns

Antimicrobial activity of sesquiterpene lactones isolated from traditional medicinal plant, Costus speciosus (Koen ex.Retz.) Sm

<p>Abstract</p> <p>Background</p> <p><it>Costus speciosus </it>(Koen ex.Retz.) Sm (Costaceae) is an Indian ornamental plant which has long been used medicinally in traditional systems of medicine. The plant has been found to possess diverse pharmacological activities. Rhizomes are used to treat pneumonia, rheumatism, dropsy, urinary diseases, jaundice, skin diseases and leaves are used<b/>to treat mental disorders.</p> <p>Method</p> <p>Antibacterial and antifungal activities were tested using Disc diffusion method and Minimum Inhibitory <b>Concentration </b>(MIC). Column chromatography was used to isolate compounds from hexane extract. X-ray crystallography technique and GC-MS analysis were used to identify the compounds</p> <p>Results</p> <p>Antibacterial and antifungal activities were observed in hexane, chloroform, ethyl acetate and methanol extracts. Hexane extract of <it>C.speciosus </it>showed good activity against tested fungi also. Two sesquiterpenoid compounds were isolated (costunolide and eremanthin) from the hexane extract. Both the compounds did not inhibit the growth of tested bacteria. But, both the compounds inhibited the tested fungi. The compound costunolide showed significant antifungal activity. The MIC values of costunolide were; 62.5 μg/ml against <it>Trichophyton mentagrophytes</it>, 62. μg/ml against <it>T. simii</it>, 31.25 μg/ml against <it>T. rubrum </it>296, 62.5 μg/ml against <it>T. rubrum </it>57, 125 μg/ml against <it>Epidermophyton floccosum</it>, 250 μg/ml against <it>Scopulariopsis </it>sp, 250 μg/ml against <it>Aspergillus niger</it>, 125 μg/ml against <it>Curvulari lunata</it>, 250 μg/ml against <it>Magnaporthe grisea</it>.</p> <p>Conclusion</p> <p>Hexane extract showed promising antibacterial and antifungal activity. The isolated compound costunolide showed good antifungal activity.</p

Brood parasite and host eggshells undergo similar levels of decalcification during embryonic development

Common cuckoos (Cuculus canorus) are obligate brood parasites that lay their eggs in the nests of other (host) species. To increase the likelihood of successful parasitism, common cuckoos lay eggs with thicker and structurally stronger eggshells than those of their hosts and non-parasitic relatives. Although hatching from thicker eggshells requires greater effort and may impose physiological costs on cuckoo embryos during hatching, it is unclear whether cuckoo eggshells are indeed thicker at the time of hatching. This is because avian embryos decalcify the innermost eggshell layer (mammillary layer) for organ development during embryogenesis, reducing eggshell thickness and making hatching easier. Therefore, common cuckoo eggshells may undergo a greater degree of decalcification during embryonic development to facilitate hatching from an initially thicker-shelled egg. We used scanning electron microscopy to test this hypothesis by comparing the thickness and degree of decalcification of eggshells collected either before incubation or after hatching. We found that cuckoo eggshells undergo similar degrees of decalcification during embryonic development as the thinner eggshells of a host that lays similarly sized eggs, the great reed warbler (Acrocephalus arundinaceus). Cuckoo eggshells hence remain thicker than eggshells of this host throughout embryogenesis, supporting the predicted trade-off between the benefits of laying puncture resistant eggs and the physiological costs associated with hatching

Anti-Inflammatory properties of Salograviolide A purified from Lebanese plant Centaurea ainetensis

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