New Zealand Room 2 Wednesday, December 7th 2011
16:30 Effects of a highly interactive species, the black-tailed prairie dog, on urban avian diversity Magle, SB*, Lincoln Park Zoo
; Salamack, KA, Wildlife Habitat Council; Crooks, KR, Colorado State University; Reading, RP, Denver Zoo
Urbanization and habitat fragmentation have the potential to influence bird communities, and these phenomena, as well as ongoing lethal control measures, have also reduced the range of the black-tailed prairie dog (Cynomys ludovicianus) by an estimated 98% since the beginning of the 20th century. Prairie dogs are highly interactive species that can influence bird species diversity, abundance, and richness. Past research on prairie dog-bird dynamics was conducted on native prairie and few studies investigated whether these interactions persist in an urban setting. We performed bird counts on 20 habitat fragments (ten colonized by prairie dogs, ten uncolonized by prairie dogs) spread throughout the Denver metropolitan area, and calculated Shannon-Weiner diversity, richness, and counts of individuals within specific avian guilds. Mean avian diversity and richness increased with increasing fragment connectivity, and decreased on fragments isolated for longer periods of time. Avian diversity and richness did not differ between fragments with prairie dogs and fragments without prairie dogs, suggesting that this element of the keystone role of prairie dogs is not fully retained in urban habitat. Future studies of the role of prairie dogs as keystone species in urban systems should include other taxa as well as incorporate the role of the urban matrix surrounding prairie dog habitat.
16:45 Can pocket parks support suburban birds in a compact city? Stagoll, K*, Fenner School of Environment and Society, Australian National University
; Manning, AD, Fenner School of Environment and Society, Australian National University; Knight, E, Fenner School of Environment and Society, Australian National University; Fischer, J, Faculty of Sustainability, Leuphana University Lueneburg; Lindenmayer, DB, Fenner School of Environment and Society, Australian National University
The desire to improve urban sustainability is motivating many city planners to adopt growth strategies that increase residential density, leading to substantial changes in the urban form. In Australia, for example, Canberra is moving from a â€śgarden cityâ€ť approach of large residential blocks with extensive private open space, to a â€ścompact cityâ€ť plan of small blocks with high levels of impervious surface cover. What affect this change will have on biodiversity remains unclear, but it is expected that the role of public green space in providing wildlife habitat will become critical. In our study, we explored the role of suburban â€śpocketâ€ť parks as habitat for birds, and how this role changes with different urban forms. We looked at the effects of several scales, including the vegetation structure within the park, the amount of green space within the neighbourhood, and the housing structure of the suburb. We also considered the importance of physical connectivity between the park and other public green space. We conclude that pocket parks, especially those retaining large native trees, (1) provide foraging and nesting resources for a wide diversity of birds, (2) help maintain a continuum of stepping stones throughout suburban areas, and (3) may function as suburban refugia as cities become more compact.
17:00 Urbanisation and its effects on the distribution and activity of insectivorous bats and their insect prey in Sydney, Australia Threlfall, C*, Evolution and Ecology Research Centre, School of Biological Earth and Environmental Sciences, University of New South Wales, Sydney, NSW 2052, Australia
; Penman, T , Forest Science Centre, Industry and Investment NSW, Beecroft, NSW, Australia; Law, B, Forest Science Centre, Industry and Investment NSW, Beecroft, NSW, Australia; Banks, P, School of Biological Sciences, University of Sydney, NSW 2006, Australia
Urbanisation has an uneven impact on wildlife but the mechanisms that determine winners and losers in the modified environment are poorly known. We investigated three hypothesised mechanisms influencing spatial patterns of insectivorous bats in Sydney, Australia; landscape heterogeneity (diversity of land uses), productivity (as indexed by landscape geology and insect biomass) and trait diversity. Bat species richness and activity (bat passes/night) were collected using ultrasonic bat detectors at 29 randomly selected landscapes (urban; suburban; and vegetated, each 25 km2) across 113 sites comprising various land uses and productivities. We found greater bat activity and more species of bat in suburban landscapes on fertile geologies. Productivity and urbanisation interacted with species traits to structure the bat community; open-adapted bats were associated with areas of greater urbanisation, while clutter-adapted bats were associated with greater amounts of bushland. The prey base of bats (nocturnal insect biomass) was also greater within fertile suburban landscapes in both natural and human modified areas. Our data demonstrates processes determining spatial patterns of urban microbats and highlight areas for conservation action. Our results suggest that landscape structure coupled with human activities can favour certain species traits, and may shift trophic relationships in cities as they alter the bottom of the food web in ways that impact upon higher trophic levels.
17:15 Predicting the effect of urban noise on acoustic communication in birds Parris, KM, University of Melbourne
; McCarthy, MA*, University of Melbourne
Continuing urbanisation of the planet is changing the physical structure of habitats for non-human species, but also markedly changing their acoustic environment. Urban noise interferes with acoustic communication in a range of animals including birds, with potentially profound impacts on fitness. However, a general, mechanistic theory to predict which species of birds will be most affected by urban noise, and the magnitude of any effects, is lacking. We will present a model to predict the decrease in communication distance experienced by birds when moving from natural to urban habitats (or when natural habitats are urbanised). The model predicts that the magnitude of the decrease is largely a function of signal frequency; however, the relationship between the former and latter is not monotonic. A meta-analysis of observed changes in birdsong in urban noise supports this prediction for signals in the frequency range of 1.5 â€“ 4 kHz. The model can be used to assess the likely impacts of urban noise on bird assemblages around the globe, including which species will suffer the greatest acoustic interference, and which will show the greatest behavioural and population-level responses to urban noise.
17:30 Relative roles of urban greenery and landscape variables in promoting bird and butterfly communities in Singapore Teo, S, Centre for Sustainable Asian Cities, School of Design and Environment, National University of Singapore
; Chong, KY*, Department of Biological Sciences, National University of Singapore; Kurukulasuriya, BR, Centre for Remote Imaging, Sensing and Processing, National University of Singapore; Chung, YF, Centre for Sustainable Asian Cities, School of Design and Environment, National University of Singapore; Tan, HTW, Department of Biological Sciences, National University of Singapore
With ever-growing urbanization, conservation ecologists can no longer focus their attention solely on intact ecosystems. In heavily human-modified sites such as cities, urban greenery plays a major role in mitigating the hostility of the built environment for wildlife. Studies on the effects of urban greenery have seldom investigated the relative roles of cultivated and spontaneous vegetation on promoting urban wildlife. We use bird and butterfly surveys and satellite-image derived urban landscape information to test the effects of cultivated tree, shrub, ground cover, spontaneous vegetation cover, road lane density, impervious cover, and building height on bird and butterfly species richness. Spontaneous vegetation cover trumps other forms of urban greenery in promoting bird and butterfly species richness, while road lane density had strong negative effects. No significant additional effects were found for impervious cover and building height. These preliminary findings suggest that pockets of natural and semi-natural areas are critical for maintenance of high biodiversity in urban areas, while traffic networks need to be carefully designed to reduce their impacts on urban wildlife.
17:45 Impact of urbanization on flower visitors assessed with a country-wide monitoring program based on citizen science. Deguines N*, Museum national d'Histoire naturelle
; Fontaine C, Museum national d'Histoire naturelle; Julliard R, Museum national d'Histoire naturelle
Pollinators play a key role in ecosystems functioning. Decline in both honey bee and wild pollinators have recently been documented and habitat loss coupled with agricultural intensification have been highlighted as important drivers of this pollination crisis. The effect of urbanization is less documented, and it has been proposed that due to high availability of floral resources and low pesticide level, urban areas may act as refuges for pollinators. We tested this hypothesis using data from a new monitoring program based on citizen science, where observers sample plant-insect interactions following a standardized protocol. By the end of 2010, about 13000 interactions have been sampled in 2200 localities distributed all across France. Our results indicate first that the majority of flower visitors are negatively affected by urbanization. Second, sensitivity to urbanization differs among insect orders, with hymenopterans appearing more tolerant than dipterans and lepidopterans. Third, within insect orders, urbanizationâ€™s sensitivity seems to be related to the complexity of the insect life cycle, with for example, parasitic hymenopterans that appear to be more sensitive than non-parasitic ones. These results do not support the hypothesis that urban areas are refuges for pollinators. Citizen science seems an appropriate methodology to study pollinatorâ€™s communities and their responses to large-scale environmental characteristics.
18:00 A paradigm shift: revisiting Noss (1990) for a comprehensive framework for biodiversity-assessment Chivers, SJ*, University of New England, NSW, Australia
; Oliver, I, NSW Department of Environment, Climate Change, and Water, Australia; Gross, CL, University of New England, NSW, Australia
Human impacts on the environment result in the loss of biodiversity processes and patterns, and not only species, from the landscape. Therefore a necessary response of conservation scientists should be the development of a scientifically rigorous biodiversity-assessment framework which is comprehensive in evaluating the multi-faceted nature of biodiversity losses. Ensuring such a framework would remain practicable for biodiversity regulation and management agencies could be problematic as the term biodiversity now circumscribes a complex omniscience merging scientific concepts with socio-economic demands. However based on a review of the current major paradigms relevant to biodiversity-assessment (ecosystem health, ecological integrity, and various species-level approaches), we suggest that a return to a more scientifically rigorous approach is now warranted. We therefore suggest a paradigm-shift by revisiting but also further developing a three-component approach to biodiversity-assessment originally put forward more than two decades ago by Noss (1990, Conserv. Biol. 4(4):355-364). This reworked framework comprehensively evaluates three components of biodiversity (function, structure, and composition; or biodiversity processes, patterns, and species, respectively) and remains scientifically rigorous by accounting for the ecological and biophysical mechanisms that drive the status of components and by targeting specific biodiversity processes and patterns.
18:15 The habitat value of indigenous perennial tree-crop systems in a highly fragmented ecosystem of Mediterranean Australia Gove, AD*, Dept. Environment and Agriculture, Curtin University
; Woodall, GS, Centre of Excellence in Natural Resource Management, University of Western Australia
The Western Australian Wheatbelt is one of Australiaâ€™s most heavily cleared regions and possesses limited potential for reserve expansion. Hence, it is imperative that management consider the role of the landscape matrix in maintaining species by the provision of habitat and increasing landscape connectivity. Perennial tree-crops are of increasing interest in the region and cultivation far exceeds the area covered by conventional revegetation (~3x). Hence their habitat value should be taken into account. In this study we surveyed bird and wasp assemblages in plantations of the hemiparasitic sandalwood (Santalum spicatum) and brushwood (Melaleuca spp.) and compare these with replicated samples from annual crop (Lupin) and local native woodlands. We have found that wasp species density in tree crops is similar to woodlands, and that tree crops possess an assemblage different to that of annual crops but not necessarily resembling woodland. Sandalwood in particular exhibits bird species densities similar to that of woodlands and provides habitat for several woodland-dependent species. Further analysis will examine whether the tree crops provide a seasonal refuge when on-farm resources are lowest. At this point we suggest that indigenous perennial tree crops can go some way to increasing the extent of habitat for some woodland-dependent species, and likely increase connectivity within highly fragmented Mediterranean landscapes.