A response to Gatali and Wallin (2015) Bird diversity in the savanna habitats of Akagera National Park,Rwanda, in the post-war recovery period

The paper ‘Bird diversity in the savanna habitats of Akagera National Park, Rwanda, in the post-war recovery period’ by Gatali and Wallin (Ostrich 86(3): 267–276, 2015) makes several claims for new species records for Akagera National Park and Rwanda. We found that Gatali and Wallin recorded several species considered very rare in Rwanda and new discoveries; these findings often contradicted the existing literature. We doubt the validity of 34 species records and we aim to demonstrate that these claims are mostly the result of misidentification or human error and consider that future researchers should use their findings with caution. Some findings around more common species may be validated through further studies and we encourage others to conduct fieldwork in Akagera National Park.     

Impact of flowering on bird community dynamics in some central Victorian eucalypt forests

Many species of Eucalyptus in Australia provide copious amounts of nectar during their reproductive seasons. The nectar is used by many animal species but especially by birds, insects and some bats, which act as pollinators. One of the major features of eucalypt flowering in southern Australia is the patchy, asynchronous flowering of different species, which appears to drive mass nomadism of nectarivorous birds among regions and among habitats. Here we explore whether flowering asynchrony or climate is primarily responsible for the influxes and effluxes of vast numbers of nectarivorous birds in central Victoria, Australia. By using a structured sampling program, we show that winter flowering by red ironbark Eucalyptus tricarpa is the most likely agent controlling avian-nectarivore dynamics rather than climatic differences among regions. Densities and species richness of nectarivores, and numbers of nectarivory events, are all closely related to measures of flowering intensity. However, nonnectarivores, such as insectivores and granivores, show no relationships with either habitat or region. We discuss how dependence on a patchily distributed but highly rewarding resource such as nectar influences population densities and community structure in birds.     

Area and the latitudinal diversity gradient for terrestrial birds

We tested the hypothesis that area represents the primary explanation for the latitudinal diversity gradient using breeding terrestrial birds of North America, the northern Palearctic, Australia and the Afrotropics as our focal group. We tested two propositions inherent to the area hypothesis: (1) tropical biomes are larger than extra-tropical biomes, and (2) there is a significant species-area relationship for birds at the biome scale of resolution. Using a more realistic definition of biomes which incorporates the effects of both energy and water, we find no support for either proposition, leading us to conclude that the area per se does not explain terrestrial latitudinal diversity gradients.     

The role of land cover in bioclimatic models depends on spatial resolution

Aim We explored the importance of climate and land cover in bird species distribution models on multiple spatial scales. In particular, we tested whether the integration of land cover data improves the performance of pure bioclimatic models. Location Finland, northern Europe. Methods The data of the bird atlas survey carried out in 1986–89 using a 10 × 10 km uniform grid system in Finland were employed in the analyses. Land cover and climatic variables were compiled using the same grid system. The dependent and explanatory variables were resampled to 20‐km, 40‐km and 80‐km resolutions. Generalized additive models (GAM) were constructed for each of the 88 land bird species studied in order to estimate the probability of occurrence as a function of (1) climate and (2) climate and land cover variables. Model accuracy was measured by a cross‐validation approach using the area under the curve (AUC) of a receiver operating characteristic (ROC) plot. Results In general, the accuracies of the 88 bird–climate models were good at all studied resolutions. However, the inclusion of land cover increased the performance of 79 and 78 of the 88 bioclimatic models at 10‐km and 20‐km resolutions, respectively. There was no significant improvement at the 40‐km resolution. In contrast to the finer resolutions, the inclusion of land cover variables decreased the modelling accuracy at 80km resolution. Main conclusions Our results suggest that the determinants of bird species distributions are hierarchically structured: climatic variables are large‐scale determinants, followed by land cover at finer resolutions. The majority of the land bird species in Finland are rather clearly correlated with climate, and bioclimate envelope models can provide useful tools for identifying the relationships between these species and the environment at resolutions ranging from 10 km to 80 km. However, the notable contribution of land cover to the accuracy of bioclimatic models at 10–20‐km resolutions indicates that the integration of climate and land cover information can improve our understanding and model predictions of biogeographical patterns under global change.     

新疆伊犁河湿地及周边夏季鸟类调查初报

2006年6～8月,调查了新疆伊犁河湿地及其周边夏季鸟类,共记录到16目36科96种,种群数量为3110只,水鸟占优势,共57种.其中复候鸟52种、留鸟33种、旅鸟11种;在85种繁殖鸟中,古北界52种、东洋界8种、广布种25种,分别占总种数的61.18%、9.41%、29.41%.有国家I、Ⅱ级保护鸟类13种,新疆特有种或亚种17种.鸟类生态分布显示,下游三道河一伊犁河大桥地段拥有较丰富的鸟类种群.通过调查,提出了一些鸟类保护对策.     

A low degree of fatty acid unsaturation leads to high resistance to lipid peroxidation in mitochondria and microsomes of different organs of quail (Coturnix coturnix japonica)

Birds – particularly long-lived species – have special adaptations for preventing tissue damage caused by reactive oxygen species. The objective of the present study was to analyse the fatty acid composition and non-enzymatic lipid peroxidation of mitochondria and microsomes obtained from liver, heart and brain of quail (Coturnix coturnix japonica), a short-lived bird. Fatty acids located in total lipids of rat liver, heart and brain mitochondria and microsomes were determined using gas chromatography and lipid peroxidation was evaluated using a chemiluminescence assay. The unsaturated fatty acid content found in mitochondria and microsomes of all tissue examined was approximately 50 and 40%, respectively with a prevalence of C18:1 n9. The C18:2 n6 content in brain mitochondria was significantly lower as compared to liver and heart mitochondria. Whereas the C20:4 n6 content in mitochondria from all tissues examined and brain microsomes was approximately 6%, liver and heart microsomes exhibited lower values. C22:6 n3 was absent in liver mitochondria, very low content in liver microsomes and heart organelles (between 0.5 and 1%) and high content in brain organelles, with mitochondria having the highest value (11%). Whereas liver and heart organelles were not affected when subjected to lipid peroxidation, brain mitochondria were highly affected, as indicated by the increase in chemiluminescence and a considerable decrease of C20:4 n6 and C22:6 n3. These results indicate that a low degree of fatty acid unsaturation in liver and heart organelles of quail, a short-lived bird, may confer advantage by decreasing their sensitivity to lipid peroxidation process.     

Two aberrant serpent-eagles may be visual mimics of bird-eating raptors

Two independent cases of visual mimicry involving snake-eating eagles as mimics and more powerful bird-eating hawks as models are proposed. One pair of species is formed by the sympatric West African Serpent-eagle Dryotriorchis spectabilis and Cassin's Hawk Eagle Spizaetus africanus (= Aquila africana ), inhabiting the tropical forests of the African Gulf of Guinea. The second case involves the Madagascar Serpent-eagle Eutriorchis astur and the Madagascar Goshawk Accipiter henstii , both sympatric and endemics of forests in Madagascar. Similarity in plumage colour and pattern as well as in body size and proportions are remarkable in both cases. The species mimicry pairs are in both cases not closely related phylogenetically and greatly differ in diet, making it unlikely that common ancestry or shared foraging strategies explain the resemblance in plumage coloration and pattern. Mimicry may have evolved because the mimic serpent-eagles obtain (the following hypotheses are not mutually exclusive): (1) a foraging advantage by deceiving their snake prey as they may not flee from bird-eating raptors such as the models, (2) a lowered predation or harassment by the models or other predators, and/or (3) reduced mobbing by small birds, which tend to avoid bird-eating raptors. Alternatively, the similarities in plumage described here may be the result of random convergence due to constraints in the evolution of plumage colours and patterns in diurnal raptors.     

Sperm head abnormalities are more frequent in songbirds with more helical sperm: A possible trade‐off in sperm evolution

Sperm morphology varies enormously across the animal kingdom. Whilst knowledge of the factors that drive the evolution of interspecific variation in sperm morphology is accumulating, we currently have little understanding of factors that may constrain evolutionary change in sperm traits. We investigated whether susceptibility to sperm abnormalities could represent such a constraint in songbirds, a group characterized by a distinctive helical sperm head shape. Specifically, using 36 songbird species and data from light and scanning electron microscopy, we examined among‐species correlations between the occurrence of sperm head abnormalities and sperm morphology, as well as the correlation between sperm head abnormalities and two indicators of sperm competition. We found that species with more helically shaped sperm heads (i.e., a wider helical membrane and more pronounced cell waveform) had a higher percentage of abnormal sperm heads than species with less helical sperm (i.e., relatively straight sperm) and that sperm head traits were better predictors of head abnormalities than total sperm length. In contrast, there was no correlation between sperm abnormalities and the level of sperm competition. Given that songbird species with more pronounced helical sperm have higher average sperm swimming speed, our results suggest an evolutionary trade‐off between sperm performance and the structural integrity of the sperm head. As such, susceptibility to morphological abnormalities may constrain the evolution of helical sperm morphology in songbirds.     

Bird species of black water inundation forests in the Jaú National Park (Amazonas state, Brazil): their contribution to regional species richness

We compared the relative contribution of blackwater inundation forest (igapó) and unflooded (terra firme) forest for regional bird species diversity in the lower Rio Negro region. For analyses of habitat preference we used mist-net samples and an unpublished bird species check-list. The igapó forest had lower bird species diversity than the terra firme forest. However, some 14% of the forest bird species in the region are restricted to igapó forest. Species composition was found to be distinct between the understories of the two forest types. Common forest bird guilds in the Neotropics such as ant-following birds avoid igapó forest. The differential habitat selection among birds in the inundated and unflooded forest is likely to result from vegetation structure and biological interactions such as aggressive behaviour. Since the inundated forest has a typical biota, conservation efforts needs to be directed to protect these habitats. Unfortunately, inundation forests are threatened by several human actions, especially dam construction. The extent of protected areas in the Brazilian Amazon is insufficient for the adequate protection of the inundated habitats, because it includes only 3% of the total area.