Madhusudan Katti

A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers.

Urbanization contributes to the loss of the worlds biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the worlds cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

Linking Optimal Foraging Behavior to Bird Community Structure in an Urban‐Desert Landscape: Field Experiments with Artificial Food Patches

Urban bird communities exhibit high population densities and low species diversity, yet mechanisms behind these patterns remain largely untested. We present results from experimental studies of behavioral mechanisms underlying these patterns and provide a test of foraging theory applied to urban bird communities. We measured foraging decisions at artificial food patches to assess how urban habitats differ from wildlands in predation risk, missed‐opportunity cost, competition, and metabolic cost. By manipulating seed trays, we compared leftover seed (giving‐up density) in urban and desert habitats in Arizona. Deserts exhibited higher predation risk than urban habitats. Only desert birds quit patches earlier when increasing the missed‐opportunity cost. House finches and house sparrows coexist by trading off travel cost against foraging efficiency. In exclusion experiments, urban doves were more efficient foragers than passerines. Providing water decreased digestive costs only in the desert. At the population level, reduced predation and higher resource abundance drive the increased densities in cities. At the community level, the decline in diversity may involve exclusion of native species by highly efficient urban specialists. Competitive interactions play significant roles in structuring urban bird communities. Our results indicate the importance and potential of mechanistic approaches for future urban bird community studies.

Stewardship of the Biosphere in the Urban Era

We are entering a new urban era in which the ecology of the planet as a whole is increasingly influenced by human activities (Ellis 2011; Steffen et al. 2011a, b; Folke et al. 2011). Cities have become a central nexus of the relationship between people and nature, both as crucial centres of demand of ecosystem services, and as sources of environmental impacts. Approximately 60 % of the urban land present in 2030 is forecast to be built in the period 2000–2030 (Chap. 21). Urbanization therefore presents challenges but also opportunities. In the next two to three decades, we have unprecedented chances to vastly improve global sustainability through designing systems for increased resource efficiency, as well as through exploring how cities can be responsible stewards of biodiversity and ecosystem services, both within and beyond city boundaries.

Tests of absolute photorefractoriness in four species of cardueline finch that differ in reproductive schedule

SUMMARY Species with different reproductive schedules may differ in how they respond to the annual change in photoperiod (the adaptive specialization hypothesis). Seasonally breeding species are predicted to use photorefractoriness to terminate reproduction prior to inclement conditions in autumn and winter, whereas opportunistically breeding species may not exhibit photorefractoriness. We tested for absolute photorefractoriness in four species of cardueline finch that differ in their reproductive schedules: opportunistically breeding red crossbills, flexibly breeding pine siskins, and seasonally breeding Cassins finches and gray-crowned rosy-finches. Field observations indicated that all four species regress their gonads and begin prebasic feather molt in late summer or autumn. However, exposure to a long day photoperiod in autumn (24 h:0 h L:D) resulted in elevation of gonadotropins and testicular recrudescence in all species except Cassins finches. Thus, by this criterion, some of the seasonally breeding species tested here did not exhibit absolute photorefractoriness. These results indicate that phylogenetic history needs to be taken into account when considering the adaptive nature of photoperiod response systems.

Sub-regional Assessment of India: Effects of Urbanization on Land Use, Biodiversity and Ecosystem Services

India is increasingly marked by the growing influence of urban areas, with large-scale, distal impacts on rural environments across the country. These changes will impact land cover, natural habitats, biodiversity and the ecosystem services that underpin human well-being.

Birds of a feather: Interpolating distribution patterns of urban birds

Geostatistical methods provide valuable approaches for analyzing spatial patterns of ecological systems. They allow for both the prediction and visualization of ecological phenomena, a combination that is essential for the conceptual development and testing of ecological theory. Yet, many ecologists remain unfamiliar with the application of these techniques. Here, we apply the methodology of geostatistics to an urban avian census in order to investigate and illustrate the utility of these tools. We derive habitat probability maps for three bird species known to differentially occupy the urban to rural gradient within the Phoenix metropolitan area and surrounding desert (Arizona, USA). We aggregated avian censuses conducted seasonally at 40 sites over two years and applied two processes process of interpolation, ordinary Kriging and indicator Kriging, and compared both methods. Ordinary Kriging interpolates values between measurements; however, it requires normally distributed data, which is commonly invalidated in ecological censuses. While indicator Kriging is not able to produce numerical predictions of measurements, it has the advantages of not requiring normally distributed data and requiring fewer statistical decisions. Each of the species exhibited strong deviations from normality due to many observations of zero. Given the skewness of the data, we anticipated that indicator Kriging would be a more appropriate method of interpolation. However, we found that both methods adequately captured spatial distribution of the three species and are sufficient for creating distribution maps of avian species. With additional census monitoring, Kriging can be used to detect long-term changes in population distribution of avian and other wildlife populations.

Singing in the sky: song variation in an endemic bird on the sky islands of southern India

Birdsong structure is known to vary across different scales of geographical separation, from differences between neighbours in a habitat to populations across continents. The high-elevation regions of the Western Ghats mountains in southern India form ‘sky islands’ containing the unique Shola habitat. Bird species on such sky islands are often specifically adapted to habitats typical of these islands while populations on different islands may have been geographically isolated over varying periods of time. Forest fragmentation can intensify the effects of such isolation by affecting species dispersal processes. We examined the effects of genetic differentiation across populations on the song of a threatened, endemic bird, the white-bellied shortwing, Brachypteryx major, on different islands of this sky island system. We compared songs from three populations, one of which on one island was genetically distinct from the other two populations on another island. These two populations were genetically similar but separated by recent deforestation. We recorded songs from 23 individuals and characterized 572 songs by 13 parameters. Multivariate analyses revealed significant differences in song between the three populations, with the genetically distinct populations across the two islands being the most differentiated. This was supported by a visual and aural examination of spectrograms that revealed characteristic qualitative differences in songs across these populations. Finally, this study corroborates accepted patterns of congruence between song and genetic divergence across islands and also highlights the difference in song between anthropogenically fragmented, but genetically similar populations, possibly owing to cultural drift. 2011 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.

Genome Sequence of a Multidrug-Resistant Strain of Bacillus pumilus, CB01, Isolated from the Feces of an American Crow, Corvus brachyrhynchos

ABSTRACT Avian species have the potential to serve as important reservoirs for the spread of pathogenic microorganisms. Here, we report the genome sequence of a drug-resistant strain of Bacillus pumilus, CB01, isolated from the feces of an American crow, Corvus brachyrhynchos.

Mastering Natural Selection to Shape a Human Superorganism

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