Rubén Ortega-Álvarez

Spreading the Word: The Ecology of Urban Birds Outside the United States, Canada, and Western Europe

— 415 — The Auk, Vol. 128, Number 2, pages 415−418. ISSN 0004-8038, electronic ISSN 1938-4254.  2011 by The American Ornithologists’ Union. All rights reserved. Please direct all requests for permission to photocopy or reproduce article content through the University of California Press’s Rights and Permissions website, http://www.ucpressjournals. com/reprintInfo.asp. DOI: 10.1525/auk.2011.10082 Ruben ORtega-AlvaRez1 and Ian MacgRegOR-FORs2,3

Feathering the Scene: The Effects of Ecological Restoration on Birds and the Role Birds Play in Evaluating Restoration Outcomes

Ecological restoration is a promising strategy to reverse biodiversity loss from habitat degradation worldwide. Historically, animals have received little attention within restoration activities, but in the last decade birds have been widely incorporated into restoration ecology research. Increasing our knowledge regarding birds within the restoration process should aid the development of novel approaches to perform restoration activities that consider all the components of ecosystems. In this review, we compile the literature related to birds and the restoration process, extract its general trends, summarize restoration recommendations, identify knowledge gaps, and suggest areas for future research. We classified the reviewed literature into 4 themes: 1) ecological dynamics; 2) habitat restoration for bird conservation; 3) birds as bioindicators of restoration outcomes; and 4) birds as guides for the restoration process. In general, research from temperate zones has been performed mainly within the United States (67% of reviewed literature), and our understanding of tropical ecosystems is very incomplete. The majority of reviewed literature (64.8%) analyzed the ornithological component of the restoration process from an ecological dynamics approach. Based on our findings, we suggest that particular properties of restoration activities (e.g., size of restored sites, habitat type, characteristics of contiguous habitats) should be contemplated when considering birds within the restoration context.

Birds at the urban fringe: avian community shifts in different peri-urban ecotones of a megacity

Cities can be regionalized in intra-urban and peri-urban areas. The space between urban areas and adjacent systems represents an ecological transition that often acts as a semi-permeable biological filter. In this study, we assessed changes in avian community species richness, density, and composition at different peri-urban ecotones (i.e., urban-croplands, urban-grasslands, urban-shrublands) of northeastern Mexico City. Species richness was lower in the urban component of urban-grassland and urban-shrubland ecotones, while bird densities were higher in the urban components of the urban-grassland and urban-shrubland peri-urban ecotones, mainly due to the high number of urban exploiter species. However, the urban-cropland peri-urban ecotone exhibited a different pattern, with similar low bird species richness and density values between both components (urban and non-urban). A species composition analysis revealed that urban bird communities were not influenced by adjacent non-urban habitats, since the urban components of peri-urban ecotones were more similar among them than in relation to the rest of non-urban components. In summary, results of this study show that urbanization can represent an important biological filter for birds, often reducing species richness and homogenizing avian communities at local scales. As the environmental variables determining ecological processes related to the semi-permeable filter effect that urban areas pose to biodiversity might depend on urban habitats, regions, and spatial scales, further studies are needed to fully understand this phenomenon.

Trees and the City: Diversity and Composition along a Neotropical Gradient of Urbanization

In this study we assessed tree species richness, density, and composition patterns along a gradient of urbanization of a megacity. Our results show that total, native, and exotic tree densities were highest in green areas where larger spaces are considered for greening purposes. Conversely, total, native, and exotic tree species richness were highest in land uses with intermediate levels of urban development (residential, residential-commercial areas). Not finding highest tree species richness in less developed urban areas suggests that cultural factors may shape the array of species that are planted within cities. Supporting this, tree composition analyses showed that green areas are comprised of different tree species when compared to the rest of the studied urban land uses. Thus, our results suggest that, to increase the ecological quality of cities, residents and managers should be encouraged to select a greater variety of trees to promote heterogeneous green areas.

Restoration planning to guide Aichi targets in a megadiverse country

Ecological restoration has become an important strategy to conserve biodiversity and ecosystems services. To restore 15% of degraded ecosystems as stipulated by the Convention on Biological Diversity Aichi target 15, we developed a prioritization framework to identify potential priority sites for restoration in Mexico, a megadiverse country. We used the most current biological and environmental data on Mexico to assess areas of biological importance and restoration feasibility at national scale and engaged stakeholders and experts throughout the process. We integrated 8 criteria into 2 components (i.e., biological importance and restoration feasibility) in a spatial multicriteria analysis and generated 11 scenarios to test the effect of assigning different component weights. The priority restoration sites were distributed across all terrestrial ecosystems of Mexico; 64.1% were in degraded natural vegetation and 6% were in protected areas. Our results provide a spatial guide to where restoration could enhance the persistence of species of conservation concern and vulnerable ecosystems while maximizing the likelihood of restoration success. Such spatial prioritization is a first step in informing policy makers and restoration planners where to focus local and large-scale restoration efforts, which should additionally incorporate social and monetary cost-benefit considerations.

Notes on the breeding behavior of the Bumblebee Hummingbird (Atthis heloisa), an endemic species of Mexico: nest, courtship displays, and altitudinal movements

ABSTRACT The Bumblebee Hummingbird (Atthis heloisa) is an endemic bird to Mexico. Its natural history is poorly known, particularly its breeding biology. We provide novel and complementary information that enriches the biological knowledge on the species. We describe a nest of the Bumblebee Hummingbird found in Northern Oaxaca and characterize the nest site. The nest was mainly assembled with mosses and lichens; however, we recorded females transporting hairs of the invasive fern Pteridium sp. and seeds of the bromeliad Catopsis sp. for nest construction. Males were noisy and conspicuous while females were secretive; thus, we suggest considering differences in detectability among sexes when studying the species. Males exhibited courtship displays that consisted of several vertical movements over females while adopting a horizontal posture, erecting the tail, emitting a bee-like sound, and fanning out the feathers of the throat toward the females. The Bumblebee Hummingbird is considered a sedentary species, but we suspect it performs altitudinal movements in search of cloud forests during spring and summer and humid pine-oak forests during winter and autumn. Although the literature indicates that this hummingbird reaches breeding conditions between April and July, we recorded intense breeding activity only during January and February. It is not clear if such variation is regional or if the species could breed multiple times during the year.