Reproduction, juvenile survival and retention in an urban fox squirrel population

Fox squirrels in an urban environment had an average litter size of 2.83 (95% CI 2.5, 3.16) which was similar to rural populations. Nonetheless, the proportion of squirrels reproductively active during the summer/fall breeding season (0.73) and annually (spring + summer/fall) was higher (1.23) than previously recorded for non-manipulated rural populations. The average monthly survival rate () of urban juvenile fox squirrels during the first 14 weeks of life was higher than reported for adult populations in the area. High rates of reproduction and juvenile survival yielded high juvenile to adult ratios (juveniles/adults) averaging 0.44. Retention of juveniles after 6 months (15%) was significantly less (χ ² = 7.24, p = 0.0071) than adults/subadults (40%). Results suggest that the urban environment provides quality habitat for fox squirrels and fox squirrels in urban environments have the potential to be a source population for surrounding suburban and rural environments.     

The coexistence of Fox (Sciurus niger) and gray (S. caroliniensis) squirrels in the Chicago metropolitan area

Two species of tree squirrel inhabit the Chicago region, the fox (Sciurus niger) and gray (S. caroliniensis) squirrel. Chicago residents submitted squirrel observations and associated landscape variables via a Website, allowing us to map squirrel distributions. Data were analyzed for patterns of correlation. At a smaller scale, we did a foot survey of fox and gray squirrels in the suburb of Oak Park, replicating an earlier study and comparing results. Gray squirrels were associated with densely populated areas, parks and campuses, fox squirrels with suburban areas. Compared to gray squirrels, fox squirrels were more likely to be observed in areas of high cat density. In the suburb of Oak Park, the current trend seems to be an extension of gray squirrel distribution and a decrease in fox squirrel distribution. Our study provides support for the idea that fox and gray squirrel coexistence is facilitated by a trade-off between managing the cost of predation and foraging efficiency, gray squirrels out-competing fox squirrels in areas of high food and low predator (or pet) density.     

Effects of forest structure on the distribution of southern flying squirrels (Glaucomys volans) in urban parks

Although southern flying squirrels (Glaucomys volans) are present in many urban parks, squirrel-habitat relationships in such areas are poorly understood, limiting conservation efforts. Our objective was to quantify the effects of forest structure at multiple scales on flying squirrel distribution in New York City (NYC) parks. From 18 June–24 August 2001, we captured flying squirrels in 5 New York City parks and measured forest structure at the ground, shrub, understory, and overstory levels at trap sites. To examine the importance of forest structure to squirrels, we compared (1) habitat variables between trap stations where squirrels were captured and not captured and (2) habitat variables between parks with and without documented squirrel populations. Our data suggest that areas with forests containing smaller trees at higher densities, dense woody ground cover, and little herbaceous ground vegetation may not provide the food, cavities, ease of movement, or allow predator detection necessary to be used by or support flying squirrel populations. Other factors, such as the size and density of stumps and snags may be important to non-urban squirrel populations, but not populations in NYC parks. Because NYC parks contain almost all of the remaining woodlands within the City, forests within these areas should be a conservation priority.     

Habitat use in basking Northern water (Nerodia sipedon) and Eastern garter (Thamnophis sirtalis) snakes in urban New Jersey

The habitat use of basking northern water (Nerodia sipedon) and Eastern garter (Thamnophis sirtalis) snakes was examined along the Raritan Canal, an urbanized area of central New Jersey. There were significant differences between the two species with respect to cloud cover, canopy cover, and the distance to the path and the water, but not with respect to percent of the body exposed to the sun, and percent of the snake that was visible. Water snakes were more likely to bask on bushes, branches and logs than were garter snakes. Garter snakes basked when both the air and water temperature were lower than did water snakes. The lack of basking sites in the water suggests that those along shore are important, including the low hanging branches used by the watersnakes.     

Influence of Argentine and coastal brown ant (Hymenoptera: Formicidae) invasions on ant communities in Perth gardens,Western Australia

A survey examined the influence of Argentine (Linepithema humile (Mayr)) and coastal brown ant (Pheidole megacephala (Fabricius)) populations on other ants in the Perth metropolitan area, Western Australia. Twelve gardens (yards) were sampled; four infested by Argentine ants, three infested by coastal brown ants, and five controls where these two tramp ants were absent or collected only as isolated strays. Collection methods used were pitfall trapping and hand collection. A total of 27 species was recorded. Eight of these species, including the above two tramp ants, are non-native to the region. Pheidole megacephala was the most abundant species, comprising 95.4% of ants in P. megacephala–infested gardens. Linepithema humile comprised 92.1% of ants in L. humile–infested gardens. Other common ants were the native Iridomyrmex chasei and the introduced species Tetramorium simillimum and Tetramorium bicarinatum. The cryptic introduced species Cardiocondyla nuda and Tetramorium simillimum appear able to persist in small numbers in L. humile–infested gardens, but virtually no other ant species occurred where the coastal brown ant was well established. Mean richness, diversity, and evenness were significantly different between P. megacephala–infested and control gardens, and significantly different between L. humile–infested and control gardens. Diversity and evenness, but not richness, were significantly different between P. megacephala–infested and L. humile–infested gardens. Ordination analysis revealed that the three types of gardens had very different ant community profiles.     

Survey of feral rock doves (Columba livia) in Amsterdam, a bird-human association

We carried out a survey of the feral rock doves (Columba livia) visible in the public areas of the fourteen Town Councils in Amsterdam. The objectives were to detect the preferential locations of the feral pigeons and to obtain reference values of their population sizes in order to be able to evaluate the effect of possible control measures. We registered 354 locations were twenty or more feral pigeons were visible during feeding. In these locations, averaged over ten to twelve counts, we counted 10,056 pigeons. Moreover we observed that at another 541 locations at least once five pigeons were visible during feeding. In all 894 locations we counted, averaged over four counts, 11,885 pigeons. By Town Council, we calculated strong positive correlations between the average number of pigeons per hectare, the human population density, the number of houses and the yearly number of kilos organic waste per hectare.     

Reinventing religious land as urban open space: The case of kuang in Chiang Mai (Thailand)

Urban open spaces are highly valued for their contribution to the quality of life in the cities [Tenkel (1963). Cities and space: The future use of urban land. Baltimore:Johns Hopkins Press; Burgess, Harrison and Limb (1998). Urban Studies, 25, 455–473; Madanipour (1999). Environment and Planning B: Planning and Design, 26, 879–891]. Third world cities, for example, Chiang Mai (Thailand), are no exception with regard to the role of urban open space in achieving such a goal [Tantayanusorn (2003). Unpublished doctoral thesis. Melbourne:Royal Melbourne Institute of Technology]. However, the provision of urban open space as a social public facility is coming low in priority in comparison to other market-demanded facilities in the form of roads, car parks, clean water, electricity and the like. Such a fact was corroborated by a study conceived by Thailand's Social Research Institute (1996) which reveals that 73% of Chiang Mai population wanted more public open space.This paper aims at exploring the revitalization of existing traditional open spaces (kuang)—which is usually categorized as ‘religious land’, hence it is a religious property—in Chiang Mai as an intermediate strategy in providing the much needed public open space. In doing so, the physical and cultural characteristics of kuang have to be elaborated, while at the same time the local aspirations on urban open space were canvassed. The combined analysis of those two inquiries resulted in a proposal of kuang wat—a variance of kuang—utilization as an agent of urban open space provision in the project of achieving quality of urban life in Thai city of Chiang Mai.