Gray squirrel density, habitat suitability, and behavior in urban parks

Abstract

Increased density, increased intraspecific aggression, and a reduced fear of humans have been suggested as the more observable and frequently described characteristics of wildlife species undergoing synurbization, the process of becoming urbanized. The relationship among these variables and how they may be related to environmental variables that change with urbanization is poorly understood. In this paper we explore the relationship between density, intraspecific aggression, and reduced fear of humans in urban populations of gray squirrel. In the summer and fall of 2003 and 2004, we studied a park with a documented high density of gray squirrels, Lafayette Park, Washington, DC, and six urban parks in Baltimore, MD with unknown squirrel densities. We used linear regression (SAS Institute, SAS/STAT user's guide. SAS Institute, Cary, NC, 2005) to determine if there was a relationship (P<0.05) between squirrel density and intraspecific aggression, squirrel density and reduced fear of humans (wariness), and squirrel density and habitat suitability. We found a positive association between density and intraspecific aggression (R 2 =0.81, P<0.00). A negative relationship between density and wariness (R 2 adj ¼ 0:71, P<0.00). However, no relationship was evident between habitat suitability and squirrel density (R 2 adj ¼ À0:50, P=0.437).

Urban residents' perceptions of birds in the neighborhood: Biodiversity, cultural ecosystem services, and disservices

“…K ¼ the number of model parameters, LL ¼ model log-likelihood, DAIC c ¼ distance from the top model, and w i ¼ Akaike weight. Parker and Nilon 2008). However, the relative abundances of only crows and cowbirds were positively related to the numbers of bird feeders, and relative abundance did not increase for any predator species in response to experimental supplementation.…”

“…Collectively, these 6 predator species accounted for the majority of predation events on both robin and cardinal nests in our system (74% and 66%, respectively ;Malpass 2015). The diets of Brown-headed Cowbirds, American Crows, Common Grackles, Blue Jays, and eastern gray squirrels incorporate anthropogenic foods, including birdseed from feeders in suburban neighborhoods (Lowther 1993, Bowers and Breland 1996, Peer and Bollinger 1997, Marzluff et al 2001, Verbeek and Caffrey 2002, Marzluff and Neatherlin 2006, Parker and Nilon 2008, Smith et al 2013.…”

Ecological Drivers of Cladoceran Diversity in the Central European City (Łódź, Poland): Effects of Urbanisation and Size of the Waterbody

“…Historically, research into urban biodiversity has focused on birds (Blair, 1996;Chace and Walsh, 2006;Santoul et al, 2009;Ferenc et al, 2014), mammals (Baker and Harris, 2007;Parker et al, 2008)) and lotic ecosystems ( (2012) and Goertzen and Suhling, (2013) for Odonata diversity within urban pond habitats and Gledhill et al (2008) for invertebrate diversity within old and new urban developments. In particular, there has been a paucity of research into garden pond biodiversity (Monkay andShine, 2003, Gaston et al, 2005a) and the potential of urban ponds to serve as refugia (Chester and Robson, 2013).…”

The process of natural succession in urban areas

“…Parker and Nilon (2008) have observed squirrel densities in urban areas exceeding 33 individuals per hectare. At these high densities, intensive seed predation by squirrels can eliminate opportunities for regeneration.…”