Opposite Responses of Native and Nonnative Birds to Socioeconomics in a Latin American City.

Due to the massive increase of the urban population, a global target is to achieve sustainable cities that are sensitive to nature and environmentally just for urban dwellers. To accomplish this, it is important to understand the responses of native and nonnative birds, identify the environmental variables that promote native species and limit nonnative species, and understand how they vary among socioeconomic groups. Although many cities in the Global South exhibit strong social and environmental segregation, few studies have investigated the relationship between socioeconomics and biodiversity. Therefore, to help promote ecological justice and biodiversity conservation in the developing world, we investigated the influence of socioeconomic level and woody cover on bird species richness and abundance in the city of Santiago de Chile. We also investigated whether bird response changes with species provenance-it is important to understand the response of native birds separately from nonnative birds because they imply opposite management strategies (e.g., conservation vs. species control/eradication). Thus, we surveyed 120 sites located in residential areas of high, medium, and low socioeconomic levels across the city and fit generalized linear (mixed) models that described bird species richness and abundance for total, native, and nonnative birds according to socioeconomic level and woody vegetation cover. We found that both socioeconomic level and woody vegetation cover influenced the bird community, but their effects changed with bird species origin, having opposite effects on native and nonnative birds. Residential areas where wealthier people live supported greater species richness and abundance of native birds than residential areas where people of lower socioeconomic status live. In contrast, residential areas where vulnerable people live had greater bird abundance that was mainly composed of nonnative birds. Therefore, affluent neighborhoods provide more opportunities to encounter native birds and experience nature close to home than poorer neighborhoods. Due to woody cover having positive effects on native birds and a negative influence on nonnative birds, increasing tree and shrub cover will contribute to supporting more native birds in residential areas deprived of woody vegetation, which are commonly low socioeconomic areas. Additional variables that can explain bird response among residential areas of different socioeconomic levels need to be investigated to better understand the factors influencing the distribution of birds in cities and promote a more biodiverse and environmentally just city.

Abundance of Non-Native Birds in the City: Spatial Variation and Relationship with Socioeconomics in a South American City.

Cities commonly support a high abundance of non-native species that can affect both wildlife and human health; however, their distribution across the urban environment and their relationship with socioeconomics are not well documented. Here, we map the abundance of three non-native birds in a Latin American city-domestic pigeon (Columba livia f. domestica), house sparrow (Passer domesticus), and monk parakeet (Myiopsitta monachus)-and investigate the effect of socioeconomics on their abundance. We found that C. livia f. domestica exhibited a random distribution of abundance across the city but reached its greatest abundance in low-income areas. P. domesticus exhibited an aggregated distribution of abundance, being most abundant in the southern and western areas of the city and in low-income areas. M. monachus exhibited an aggregated distribution of abundance, being most abundant in the northeastern part of the city and reaching its greatest abundance in high-income areas. Low-income areas likely provide high abundance of food, shelter, and nesting sites for both C. livia f. domestica and P. domesticus, whereas high income areas have greater tree cover and larger trees in which M. monachus can build communal nests. Our study finds that the abundance of non-native birds varies across the city and between socioeconomic groups; therefore, targeted management is needed in different city zones to limit negative effects on native species and prevent zoonotic diseases.

Is there a relationship between socioeconomic level, vegetation cover, free-roaming cats and dogs, and the diversity of native birds? A study in a Latin American capital city.

Understanding how social and environmental factors influence biodiversity can contribute to sustainable development and promote environmental justice in cities. This knowledge is especially important in developing countries with strong social and environmental inequalities. This study investigates native bird diversity in relation to the socioeconomic level of neighborhoods, their plant cover, and the abundance of free-roaming cats and dogs in a Latin American city. Two causal hypotheses were tested: 1) socioeconomic level (defined by education and income) influence native bird diversity indirectly, as an effect mediated by plant cover, as well as directly; 2) in addition, socioeconomic conditions also influence free-roaming cats and dogs which could affect native bird diversity. To test these hypotheses, data were collected at 120 sites located in neighborhoods of different socioeconomic levels across the city of Santiago de Chile and fit to Structural Equation Models. Evidence supported the second hypothesis: in wealthier neighborhoods there was greater plant cover that, in turn, positively influenced native bird diversity; in addition, fewer free-roaming cats and dogs were found in these neighborhoods but they had no effect on native bird diversity. Results suggest that increasing plant cover, especially in more socioeconomically vulnerable neighborhoods, would contribute to urban environmental justice and more equitable opportunities to access native bird diversity.

Urbanization impacts on mammals across urban-forest edges and a predictive model of edge effects.

With accelerating rates of urbanization worldwide, a better understanding of ecological processes at the wildland-urban interface is critical to conserve biodiversity. We explored the effects of high and low-density housing developments on forest-dwelling mammals. Based on habitat characteristics, we expected a gradual decline in species abundance across forest-urban edges and an increased decline rate in higher contrast edges. We surveyed arboreal mammals in sites of high and low housing density along 600 m transects that spanned urban areas and areas turn on adjacent native forest. We also surveyed forest controls to test whether edge effects extended beyond our edge transects. We fitted models describing richness, total abundance and individual species abundance. Low-density housing developments provided suitable habitat for most arboreal mammals. In contrast, high-density housing developments had lower species richness, total abundance and individual species abundance, but supported the highest abundances of an urban adapter (Trichosurus vulpecula). We did not find the predicted gradual decline in species abundance. Of four species analysed, three exhibited no response to the proximity of urban boundaries, but spilled over into adjacent urban habitat to differing extents. One species (Petaurus australis) had an extended negative response to urban boundaries, suggesting that urban development has impacts beyond 300 m into adjacent forest. Our empirical work demonstrates that high-density housing developments have negative effects on both community and species level responses, except for one urban adapter. We developed a new predictive model of edge effects based on our results and the literature. To predict animal responses across edges, our framework integrates for first time: (1) habitat quality/preference, (2) species response with the proximity to the adjacent habitat, and (3) spillover extent/sensitivity to adjacent habitat boundaries. This framework will allow scientists, managers and planners better understand and predict both species responses across edges and impacts of development in mosaic landscapes.

The trajectory of dispersal research in conservation biology. Systematic review.

Dispersal knowledge is essential for conservation management, and demand is growing. But are we accumulating dispersal knowledge at a pace that can meet the demand? To answer this question we tested for changes in dispersal data collection and use over time. Our systematic review of 655 conservation-related publications compared five topics: climate change, habitat restoration, population viability analysis, land planning (systematic conservation planning) and invasive species. We analysed temporal changes in the: (i) questions asked by dispersal-related research; (ii) methods used to study dispersal; (iii) the quality of dispersal data; (iv) extent that dispersal knowledge is lacking, and; (v) likely consequences of limited dispersal knowledge. Research questions have changed little over time; the same problems examined in the 1990s are still being addressed. The most common methods used to study dispersal were occupancy data, expert opinion and modelling, which often provided indirect, low quality information about dispersal. Although use of genetics for estimating dispersal has increased, new ecological and genetic methods for measuring dispersal are not yet widely adopted. Almost half of the papers identified knowledge gaps related to dispersal. Limited dispersal knowledge often made it impossible to discover ecological processes or compromised conservation outcomes. The quality of dispersal data used in climate change research has increased since the 1990s. In comparison, restoration ecology inadequately addresses large-scale process, whilst the gap between knowledge accumulation and growth in applications may be increasing in land planning. To overcome apparent stagnation in collection and use of dispersal knowledge, researchers need to: (i) improve the quality of available data using new approaches; (ii) understand the complementarities of different methods and; (iii) define the value of different kinds of dispersal information for supporting management decisions. Ambitious, multi-disciplinary research programs studying many species are critical for advancing dispersal research.