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

McCleery, Robert A.

doi:10.1007/s11252-008-0074-7

Cited by 13 publications

(11 citation statements)

References 22 publications

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“…The reproductive biology of the fox squirrels we studied did not differ from other populations. McCleery () suggested that urban fox squirrel populations may grow more rapidly than rural ones (McCleery ). Some urban populations in California are expanding rapidly (King , Krause et al ), and have displaced native western gray squirrels in at least 1 urban park (Muchlinski et al ).…”

Section: Discussionmentioning

confidence: 99%

“…Fox squirrels usually breed twice annually (winter: Nov–Feb with a peak in Dec and Jan; summer: Apr–Jul, with a peak in late Jun; Allen , Brown and Yeager , Moore , Koprowski ), although summer breeding does not always occur (McCloskey and Vohs , Weigl et al ). The proportion of females breeding during a given reproductive season may vary from 0.10 to 0.83 (McCloskey and Vohs , Harnishfeger et al , Hansen and Nixon , Weigl et al , Herkert et al ), but annual proportions in rural populations have exceeded 1.0 because some females reproduce twice per year (e.g., 1.3 in 1 rural population after some females were experimentally removed [Hansen and Nixon ] and 1.2 in an unmanipulated urban population [McCleery ]). Whether these observed high annual proportions are also typical of urban settings is not clear.…”

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confidence: 99%

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Efficacy and health effects of a wildlife immunocontraceptive vaccine on fox squirrels

et al. 2013

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Continued range expansion of introduced eastern fox squirrels (Sciurus niger) in the western United States could lead to widespread damage to agricultural crops, facility infrastructures, and displacement of the native western gray squirrel (S. griseus). Because traditional management alternatives may not be feasible in many areas, public interest in the use of immunocontraceptive to control local populations has increased. We evaluated the efficacy of GonaCon™ immunocontraceptive vaccine for controlling eastern fox squirrel reproduction in Davis, California. We administered GonaCon to 33 male and 26 female fox squirrels, and a control substance to 33 males and 24 females. We subsequently compared the reproductive status, health, and serum concentrations of testosterone and progesterone of our treated and control populations. In our treated population, we also measured serum concentrations of antibodies to gonadotropin‐releasing hormone (GnRH). To determine potential side effects of the vaccine, we recorded body weight and body condition of all animals, examined injection sites during each recapture, and observed the treated squirrels in the field for signs of discomfort and impaired mobility. Over 17 months, none of the recaptured GonaCon‐treated females (n = 20) reproduced, compared to 12 of 15 control females. Treated males and females developed sufficient antibodies to GnRH to suppress reproduction, suggesting that GonaCon has the potential to be 100% effective in inhibiting reproduction in both sexes. We also observed a reduction in physical signs of reproductive activity for males (P < 0.001) and in hormone levels of both females (P < 0.001) and males (P < 0.001). Control and GonaCon‐treated animals did not differ in body weight but vaccinated squirrels had poorer body condition scores and exhibited severe injection site abscesses. The abscesses may have been caused by the GnRH conjugate used in GonaCon. In our study, GonaCon was effective in reducing eastern fox squirrel reproduction. Changes in the conjugate or its preparation may reduce the severity of associated injection site reactions. © 2013 The Wildlife Society

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Efficacy and health effects of a wildlife immunocontraceptive vaccine on fox squirrels

et al. 2013

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“…In polygynous species, a high femalebiased sex ratio in a population dominated by young age classes likely reflects a positive growth rate. For example, in an urban fox squirrel ( Sciurus niger) population with high survival and reproductive rates, the juvenile-to-adult ratio of 0.44 was higher than for rural populations, with all factors combined suggesting that the urban squirrels comprised a source population (McCleery 2009).…”

Section: Age and Sex Structurementioning

confidence: 99%

“…Emigration is likely another important component of population regulation for urban adapter mammals (McCleery 2009;Soulsbury et al 2010). Dispersal appears to be an important density-dependent mechanism in urban foxes (Gosselink 2002;Soulsbury et al 2010), given their highly-structured social systems.…”

Section: Density-dependent Factorsmentioning

confidence: 99%

Wildlife Population Dynamics in Urban Landscapes

Rodewald

Gehrt

2014

Urban Wildlife

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To say that urban wildlife populations differ from those in other landscapes is, in some ways, to state the obvious, as many studies have well demonstrated how urbanization influences pattern of occurrence and relative abundance of wildlife (e.g., Blair 1996;Marzluff et al. 2001;Sinclair et al. 2005;Chace and Walsh 2006). Identifying the specific ways in which urban and nonurban wildlife populations differ and the drivers of those differences is less understood and requires a more careful examination. The response of a species to urbanization may be the consequence of life history, and behavioral and physiological attributes that promote avoidance, tolerance, or preference for urban systems. For example, urban avoiders, or species that respond negatively to development, tend to be habitat specialists, migratory, and/or sensitive to a wide range of human activities and disturbance (Croci et al. 2008). Species that respond positively to urban development (e.g., synanthropic species, urban exploiters) are often generalists, omnivorous, multi-brooded, and behaviorally flexible. Because these suites of species differ widely in population ecology even in the absence of urbanization, we forgo a direct comparison of these groups of species and, rather, examine how urbanization affects population structure and demography of species occupying both urban and nonurban landscapes (i.e., urban adapters).As we synthesize the literature, we recognize the inherent difficulty of clearly defining a "population." What distinguishes a subpopulation from a population? For some species, this may be quite clear because of limited vagility and strong segregation among habitat types; for others, it may be unclear, particularly those with more generalist habitat requirements and extensive mobility across urban

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“…In contrast, some animals can survive and even thrive in cities (Grimm et al, ) and may benefit from increased food availability or reduced predation risk (McKinney, ). In fact, survival, body condition and fecundity are sometimes greater in urban individuals than in rural conspecifics (Lyons, Mastromonaco, Edwards, & Schulte‐Hostedde, ; McCleery, Lopez, Silvy, & Gallant, , McCleery, ). However, given the continuous human disturbance, it remains largely unknown whether urban environments are truly beneficial to some animals or whether they are merely just surviving in these stressful environments (DeStefano & DeGraaf, ).…”

Section: Introductionmentioning

confidence: 99%

No evidence of physiological stress in an urban animal: Comparison of fecal cortisol metabolites between urban and rural Eurasian red squirrels

Shimamoto

Uchida

Koizumi

et al. 2019

Ecological Research

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Over the last few decades, urban environments have been regarded as alternative habitats for wildlife. Given the continuous anthropogenic disturbance, however, it remains largely unknown whether urban environments are truly beneficial to some animals or whether the animals are merely just surviving.Glucocorticoids, which play an important role in coping with environmental challenges, are often measured as primary biomarkers of physiological stress.Chronic secretions of these hormones can have deleterious effects on animal health. Some urban stressors are constantly present and may increase the risk of chronic stress. In this study, we compared fecal cortisol metabolite (FCM) levels to evaluate stress levels between an urban and rural population of Eurasian red squirrels Sciurus vulgaris. We hypothesized that if squirrels suffer from greater stress in urban environments, their FCM levels would be significantly higher than that of rural squirrels. Our results showed that FCM levels were not significantly different between the urban and rural squirrel populations, and urban squirrels did not weigh less than rural squirrels. We conclude that the urban squirrels were not subjected to greater stress than their rural counterparts. Urban environments may be preferable for red squirrels, possibly because of release from predators and increased food availability through artificial feeding. K E Y W O R D SEurasian red squirrel, fecal cortisol metabolites, hormone, physiological stress, urbanization

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

Cited by 13 publications

References 22 publications

Efficacy and health effects of a wildlife immunocontraceptive vaccine on fox squirrels

Efficacy and health effects of a wildlife immunocontraceptive vaccine on fox squirrels

Wildlife Population Dynamics in Urban Landscapes

No evidence of physiological stress in an urban animal: Comparison of fecal cortisol metabolites between urban and rural Eurasian red squirrels

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