Species of street tree is important for southern hemisphere bird trophic guilds

Abstract Urban environments are highly modified with unique assemblages of bird species. Much of the research on urban bird assemblages comes from the northern hemisphere. Southern hemisphere bird assemblages differ from northern hemisphere assemblages in that they contain a large proportion of nectarivores. In this study we focus on bird use of street trees in Australia. We investigate the relative influence of tree species (plane tree, Platanus x acerifolia; red gums, Eucalyptus camaldulensis; jacaranda, Jacaranda mimosifolia; bottlebrush, Callistemon citrinus), season and the environment surrounding street trees, on the abundance and species richness of birds in Adelaide, South Australia. Our study considers birds in terms of granivore, nectarivore and insectivore trophic guilds. Nectarivores accounted for the greatest proportion of observations, in terms of abundance, in each of the tree species investigated. Species of street tree was a significant influence on bird use of the trees for all birds and each dietary guild. Red gums were used more than the other tree species by nectarivores, while plane trees were used more than the other trees by insectivores. Use of the tree species by granivores varied with the season. The measures of the environment surrounding street trees were largely unimportant with the exception of traffic for nectarivores in some cases. Urban avifauna use street trees and the species of tree will strongly influence its use by birds. However, the pattern of use of street tree species varied at different times of year and differed between different trophic guilds of birds. The dominance of nectarivores in the southern avifauna will likely produce different patterns of urban environment use to northern hemisphere avifaunas.     

The Effects of Ultraviolet Radiation on the Biology of Amphibians

SYNOPSIS. Potential causes for the global decline of amphibiansinclude habitat loss, disease, environmental contaminants andclimate changes. The diminishing ozone layer and consequentincrease of ultraviolet-B radiation reaching the earth's surfacehas been hypothesized to be a mortality factor, especially inhabitats otherwise undisturbed. We discuss the fundamental physicsof UV and types of biological damage after exposure. A deleteriouschange in DNA, especially the production of pyrimidine dimers,is a main effect of UVB exposure. Damaged DNA can be repairedby enzymes such as photolyase when organisms are irradiatedwith UVA or visible light. We review studies including laboratoryand field approaches on damage to amphibians from UVB exposure.Field studies in which embryos were exposed to natural sunlightor sunlight with UVB removed have shown conflicting results:some show increased embryonic mortality after UVB exposure,whereas others show that current levels of UVB are not detrimentalto amphibian embryos. The abiotic factors such as water depth,water color, and dissolved organic content of aquatic ovipositionsites effectively reduces UVB penetration through water andreduces exposure to UVB of all life history stages. Biotic factorssuch as jelly capsules around eggs, melanin pigmentation ofeggs, and color of larvae and metamorphosed forms further reduceeffectiveness of UVB penetration. We suggest areas of futureresearch to test the hypothesis of the causal connection betweencurrent UVB levels and amphibian decline.     

Colony-Site Selection Drives Management Priorities for Yelkouan Shearwater Populations

Abstract: We tested whether colony-site availability could allow for an increase in the unusually small breeding populations of yelkouan shearwater (Puffinus yelkouan) on the islands of the Port-Cros National Park (France) if feral cat eradication were undertaken. Comparisons between colony and noncolony sites indicated yelkouan shearwaters preferred deep-soiled and low-outcrop-covered coastal sites. A substrate cover, light avoidance, and sea proximity model suggested that 17.5% of unoccupied sites are suitable for colony establishment. The low proportion of suitable sites currently used by yelkouan shearwaters suggests that these colonies could be refuges and that feral cat eradication will probably lead to a breeding population increase.     

Isolation of polymorphic tetranucleotide microsatellite markers for the black‐bellied seedcracker (Pyrenestes ostrinus)

We have isolated 10 polymorphic microsatellite markers for the black‐bellied seedcracker (Pyrenestes ostrinus) from genomic libraries enriched either for (AAGG)_n or (ATCT)_n repetitive elements and characterized them in 39 individuals. The number of alleles ranged from two to 27 per locus with the observed heterozygosity ranging from 0.38 to 0.94. These markers will be useful for analysis of questions concerning parentage and population genetic structure.     

The influence of host number on the attraction of biting midges,Culicoides spp., to light traps

A preliminary study was undertaken to investigate how the number of sheep below a light‐suction trap affects the number of female Culicoides obsoletus Meigen (Diptera: Ceratopogonidae) caught. As the number of sheep increased from zero to three, the number of midges caught increased, but there appeared to be no further increase when six sheep were used. The lack of increase between three and six sheep is attributable to different activity rates on certain nights, perhaps in response to weather, and suggests, therefore, that catches in light traps increase linearly with sheep numbers, at least for small host numbers.