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opencc-zeroDec 2017View details →

Data from: Impact of urbanization on abundance and phenology of caterpillars and consequences for breeding in an insectivorous bird

Urbanization can have marked effects on plant and animal populations' phenology, population size, predator-prey interactions and reproductive success. These aspects are rarely studied simultaneously in a single system, and some are rarely investigated, e.g. how insect phenology responds to urban development. Here, we study a tri-trophic system of trees – phytophagous insects (caterpillars) – insectivorous birds (great tits) to assess how urbanization influences i) the phenology of each component of this system, ii) insect abundance and iii) avian reproductive success. We use data from two urban and two forest sites in Hungary, central Europe, collected over four consecutive years. Despite a trend of earlier leaf emergence in urban sites there is no evidence for an earlier peak in caterpillar abundance. Thus, contrary to the frequently stated prediction in the literature, the earlier breeding of urban bird populations is not associated with an earlier peak in caterpillar availability. Despite this the seasonal dynamics of caterpillar biomass exhibited striking differences between habitat types with a single clear peak in forests, and several much smaller peaks in urban sites. Caterpillar biomass was higher in forests than urban areas across the entire sampling period, and between 8.5 and 24 times higher during the first brood's chick-rearing period. This higher biomass was not associated with taller trees in forest sites, or with tree species identity, and occurred despite most of our focal trees being native to the study area. Urban great tits laid smaller clutches, experienced more frequent nestling mortality from starvation, reared fewer offspring to fledging age, and their fledglings had lower body mass. Our study strongly indicates that food limitation is responsible for lower avian reproductive success in cities, which is driven by reduced availability of the preferred nestling diet, i.e. caterpillars, rather than phenological shifts in the timing of peak food availability.

opencc-zeroDec 2015View details →

Data from: Experimental feeding regime influences urban bird disease dynamics

Wild bird feeding often results in high densities of birds, potentially facilitating transmission of disease. Wild birds are major reservoirs of many zoonotic diseases, and although a number of avian disease outbreaks have been linked to bird feeders, urban bird-feeding and its role in disease systems remains poorly studied. We examined the impacts of typical supplementary feeding practices on the health status of feeder-visiting birds at experimental feeding stations in an urban area of New Zealand. Over an 18-month period, we screened birds captured at feeding and non-feeding properties for three pathogens and four groups of parasites to determine whether feeding altered disease dynamics. We also assessed body condition. All pathogens and parasites were detected in at least one garden bird species. Feeding stations tested positive for Salmonella enterica Typhimurium on ∼7% of occasions, confirming that structures used in feeding are a potential transmission pathway. Feeding influenced some parasite infection parameters; these effects varied among host species. In silvereyes Zosterops lateralis, helminth prevalence and abundance were lower at feeding properties compared to non-feeding properties. In contrast, Eurasian blackbirds Turdus merula at feeding properties had a higher abundance of helminths. House sparrows Passer domesticus at feeding properties had a higher abundance of feather lice. Furthermore, our feeding regime significantly affected body condition in house sparrow and silvereye, though no associations between parasite parameters and body condition indices were found. Our results demonstrate that feeding practices can have varied effects on avian health, including no observable effects for some disease agents in some host species. Disease risks are present, however, thus understanding and reducing these risks should be a key goal for all stakeholders to protect birds that use feeders and other wildlife.

opencc-zeroJul 2021View details →

Strolling through a century: replicating historical bird surveys to explore 100 years of change in an urban bird community

<p>In 1898, Herbert and Alice Walter started a 5-year survey of birds in Lincoln Park, – the largest park in Chicago, IL – and summarized their data in an urban birding field guide, 'Wild Birds in City Parks'. Twenty-nine years later, William Dreuth compared the relative frequency of species between the Walter's study to their own 5-year Lincoln Park survey. Between 2012 and 2015, we replicated these surveys to investigate a century of bird diversity and community composition change in urban Chicago. While species richness did not change, community composition did. We found that 1) species with a greater diet breadth and 2) species that increased in statewide occupancy were more likely to increase in frequency over time. We conclude that factors at multiple scales brought temporal changes to Chicago's bird community. Overall, this survey highlights the slow and subtle ways in which species may respond to a century of urban intensification.</p>

Figure 2 in Urbanization impacts on the trophic guild composition of bird communities

Figure 2. Exploratory boxplot showing the richness of trophic guilds (number of trophic guilds per transect) at each urban stratum of the urban gradient. References: urban (CENTER), suburban (SUB), periurban (PERI), forested (PARK) and natural (NAT) sectors.

Figure 5 in Urbanization impacts on the trophic guild composition of bird communities

Figure 5. Biplot of redundancy analysis (RDA) showing the association between trophic guild abundance and significant habitat structure variables along the urban gradient. Arrow length indicates the importance of the variable in the model and arrow orientation, the direction of the variable increase. References: percentage of area covered by herbaceous vegetation (GRASS); pavement (PAVEM); high buildings (BHIGH) and water bodies (WATERB). Guilds: aquatic diving carnivore (AquaDivCar); aquatic diving omnivore (AquaDivOmn); aquatic filter (AquaFil); aquatic striding carnivore (AquaStrCar); aquatic striding omnivore (AquaStrOmn); bark insectivore (BarkIns); coursing aerial insectivore (CourAerIns); foliage granivore (FoliGra); foliage insectivore (FoliIns); foliage omnivore (FoliOmn); generalized granivore (GeneGra); generalized insectivore (GeneIns); generalized omnivore (GeneOmn); hawking aerial carnivore (HawkAerCar); hawking aerial insectivore (HawkAerIns); nectarivore (Nect); terrestrial granivore (TerrGra); terrestrial insectivore (TerrIns); and terrestrial omnivore (TerrOmn).

Figure 1 in Urbanization impacts on the trophic guild composition of bird communities

Figure 1. Santa Fe city and strata of the urban gradient indicated by circles. The urban matrix is represented by white and water bodies and forested areas with shades of grey. References: urban (CEN), suburban (SUB), periurban (PERI), forested (PARK) and natural (NAT) sectors.

Figure 3 in Urbanization impacts on the trophic guild composition of bird communities

Figure 3. Biplot of redundancy analysis (RDA) showing the association between the richness of each trophic guild and significant habitat structure and human disturbance variables along the urban gradient. Arrow length indicates the importance of the variable in the model and arrow orientation, the direction of the variable increase. References: percentage of area covered by trees/shrubs (TREESHRUB); herbaceous vegetation (GRASS); water bodies (WATERB); pavement (PAVEM); pedestrian rate (PEDESR); and vehicle rate (VEHICLR). Guilds: aquatic diving carnivore (AquaDivCar); aquatic diving omnivore (AquaDivOmn); aquatic filter (AquaFil); aquatic striding carnivore (AquaStrCar); aquatic striding omnivore (AquaStrOmn); bark insectivore (BarkIns); coursing aerial insectivore (CourAerIns); foliage granivore (FoliGra); foliage insectivore (FoliIns); foliage omnivore (FoliOmn); generalized granivore (GeneGra); generalized insectivore (GeneIns); generalized omnivore (GeneOmn); hawking aerial carnivore (HawkAerCar); hawking aerial insectivore (HawkAerIns); nectarivore (Nect); terrestrial granivore (TerrGra); terrestrial insectivore (TerrIns); and terrestrial omnivore (TerrOmn).

Figure 4 in Urbanization impacts on the trophic guild composition of bird communities

Figure 4. Proportion of variance of the purely environmental (Env), spatially structured environmental (EnvSpa) and purely spatial components (Spa) which explain the richness (left) and abundance (right) of trophic guilds across the Santa Fe city.

opennotspecifiedJul 2021View details →

Figure 1 in Urban heronry birds tolerate human presence more than its conspecific rural birds

Figure 1. Flight initiation distance of Ardeidae birds (4 species) in urban (N = 253) and rural habitats (N = 217) was significantly different.

opencc-zeroSep 2023View details →

Infrastructure and the ethnographic-cartographic production of urban bird species richness

<p>The qualitative bio-geographies of human geographers and the quantitative mappings of biogeographers share a goal: how to understand living with non-human life. Yet they rarely bridge the conceptual and methodological gap between them. This paper theorizes how the concept of infrastructure can bridge this ethnographic-cartographic divide. Infrastructure is not just an inanimate shell. It is also a system of relation, a dynamic patterning of socionatural form emerging out of the experiences and affective moments of its constituents. As a proof of concept, we quantified and compared urban bird species richness and frequency for Tallahassee, Florida over a 17-year period (2000–2017) for two co-occurring observational infrastructures, eBird and a wildlife rehabilitation center that serves the city. Species common to both infrastructures comprised 94% of all eBird observations and 99% of all rehab records. Their differences reflected contrasts in how the motivations for experiencing birds intersected with bird habitat preferences, behavior, and contingencies of urban history and development. eBird observations had high species richness (295 spp) and reflected the growing popularity among birds and a small number of active birders for visiting stormwater retention lakes recently modified to improve bird habitat. Rehabilitation records had a lower richness (194 spp) and exhibited a much more even distribution of bird encounters among individual residents as well as community institutions like schools, universities, law enforcement, and other government organizations. Infrastructural perspectives convey how affective and individualistic encounters with non-humans can link to emergent biogeographic mappings and how urban biodiversity is relationally and heterogeneously produced rather than simply contained in cities. </p>