Birds, Volume 2, Issue 2 (June 2021) – 6 articles

Urban green spaces (UGS), such as parks and wooded streets, are open areas with vegetation that provide sustainability to urban areas. However, their role in conserving bird diversity in neotropical cities has scarcely been analyzed. The aim of this study was to analyze the variation of bird assemblages in non-wooded streets, wooded streets, and parks in Buenos Aires City, Argentina. We compared the taxonomic and functional diversity between these habitat types. We selected five non-wooded streets, five wooded streets, and five parks in the city. Bird surveys were performed in 100 m long and 50 m wide transects. We found that taxonomic diversity had the greatest value in the parks, followed by wooded streets, and then the non-wooded streets. Functional diversity was similar between habitats. The taxonomic and functional composition changed between habitats. Non-wooded streets were dominated by the Rock Dove (Columba livia) and the Eared Dove (Zenaida auriculata), whereas parks had the highest abundance of the Picazuro Pigeon (Patagioenas picazuro) and the Rufous-bellied Thrush (Turdus rufiventris). Non-wooded streets were dominated by omnivorous and granivorous species, whereas parks had a higher abundance of herbivorous and frugivorous species. The positive association between UGS and bird diversity highlights the role of UGS as biodiversity conservation sites in neotropical cities. Full article

Anaesthetic agents and doses used can significantly impact cerebrocortical responsiveness as assessed by electroencephalography (EEG). The objective of this study was to evaluate the effect of three different halothane concentrations on the EEG of Rock Doves using measures of frequency distribution and burst suppression. Eight healthy Rock Doves (Columba livia) were anaesthetized with halothane in oxygen, their tracheas intubated and their lungs mechanically ventilated. Five minutes of EEG were recorded at three multiples of minimum anaesthetic concentration (MAC), 1× MAC (1.6%), 1.5× MAC (2.4%) and 2× MAC (3.2%), presented in ascending then descending order. Fast Fourier transformation of the raw EEG record gave the median frequency (F₅₀), spectral edge frequency (F₉₅) and the total power (P_tot). Burst suppression, expressed as inactive compared to active EEG (%), was calculated on a representative two-minute section of the raw EEG. Data were analysed using repeated-measures one-way ANOVA with Tukey post hoc correction for comparison of 1×, 1.5× and 2× MAC. Three of eight birds demonstrated negligible (<1%) burst suppression. No effect of halothane concentration on burst suppression incidence was seen. A significant decrease in all measured frequency variables (F₅₀, p = 0.04; F₉₅p = 0.02; P_totp < 0.0001) occurred between 1× and 2× MAC. Halothane anaesthesia at MAC multiples of 1×, 1.5× and 2× in the Rock Dove can be considered suitable where cortical responsiveness is desired. Full article

The Millennium Ecosystem Assessment proposed four categories of ecosystem services as regulating, provisioning, supporting and cultural. Of these, cultural services have been the most difficult to quantify despite playing a key role in developing society’s supporting services to ecosystems. By reviewing a series of case studies related to the cultural services derived from raptors, we examine relations between tangible ecosystem services and ‘knowledge’ and ‘beliefs’ as part of supporting services from human societies to ecosystems. We identified types of raptor regulating and provisioning services and patterns in service--knowledge-beliefs that defined positive or negative outcomes for raptor conservation. We also demonstrate how possible interactions between physical, experiential, physical-symbolic and representative-symbolic cultural services and between different stakeholders can create incentives or obstacles for conservation. Predictable patterns in service-knowledge-beliefs provide a framework upon which socio-cultural and ethnobiological aspects of raptor conservation may be combined with ecological research to support conservation initiatives. Based on these patterns we present examples of how cultural services might be employed to better promote raptor conservation while respecting the beliefs and traditions of stakeholders. Full article

This study evaluates the relative contribution of reproduction-based life history traits and diet to the population trends in waterbirds from southern Africa. Life history traits (clutch size, incubation period, fledging time, body mass and generation length), diet (prey weight, body lengths and number of taxa represented in its diet (NTD)) and conservation status (declining/not declining) of 163 waterbird species were reviewed. An index of diet generalism was created based on NTD. Cluster analysis was applied on life history traits to define groups of waterbirds. Binomial regressions were used to test if population trends were different across cluster groups and diet variables. Four clusters of waterbirds were defined, with most waterfowl clustering together. Species that feed on small and large prey had higher probabilities of declining (0.17 and 0.26, respectively) compared to those feeding on medium-sized prey (0.08). Amphibians, coleopterans, crustacea, molluscs and tunicates were used by species in all clusters, and the risk of waterbird populations declining further are high given the current dwindling of the prey base. The large proportions of declining species (61%) in waterbirds, which have constrained habitats, calls for continued efforts to mitigate disturbances to wetlands. Full article

To understand the social interactions among songbirds, extracting the timing, position, and acoustic properties of their vocalizations is essential. We propose a framework for automatic and fine-scale extraction of spatial-spectral-temporal patterns of bird vocalizations in a densely populated environment. For this purpose, we used robot audition techniques to integrate information (i.e., the timing, direction of arrival, and separated sound of localized sources) from multiple microphone arrays (array of arrays) deployed in an environment, which is non-invasive. As a proof of concept of this framework, we examined the ability of the method to extract active vocalizations of multiple Zebra Finches in an outdoor mesh tent as a realistic situation in which they could fly and vocalize freely. We found that localization results of vocalizations reflected the arrangements of landmark spots in the environment such as nests or perches and some vocalizations were localized at non-landmark positions. We also classified their vocalizations as either songs or calls by using a simple method based on the tempo and length of the separated sounds, as an example of the use of the information obtained from the framework. Our proposed approach has great potential to understand their social interactions and the semantics or functions of their vocalizations considering the spatial relationships, although detailed understanding of the interaction would require analysis of more long-term recordings. Full article

The Spotted Owl is a rare and declining raptor inhabiting low/middle-elevation forests of the Pacific Northwest, California, and the Southwest in the USA. It is well established that Spotted Owls select dense, mature, or old forests for nesting and roosting. High-severity fire transforms such forests into a unique forest type known as “snag forest habitat”, which the owls select for foraging. This habitat is disproportionately targeted by post-fire logging projects. Numerous recent articles have explored the influence of high-severity fire and post-fire logging on this species. Studies have shown that post-fire logging significantly reduces Spotted Owl occupancy, but efforts have generally not been made to disentangle the effects of such logging from the influence of high-severity fire alone on Spotted Owls. We conducted an assessment of published, peer-reviewed articles reporting adverse impacts of high-severity fire on Spotted Owls, exploring the extent to which there may have been confounding factors, such as post-fire logging. We found that articles reporting adverse impacts of high-severity fire on Spotted Owls were pervasively confounded by post-fire logging, and in some cases by a methodological bias. Our results indicate a need to approach analyses of high-severity fire and Spotted Owls differently in future research. Full article