Space use and home range overlap of least chipmunks in the Laramie Range Sara Locker, Garrett Smith, and Merav Ben-David Department of Zoology and Physiology University of Wyoming Body mass, which represents the energy demands of animals, has been identified as an important predictor of home range size in many terrestrial and marine mammals. Tucker, Ord, & Rogers, (2014) In most studies, only interspecific effects of body size have been explored but few addressed the effects of sexual dimorphism within species. Garland, Dickerman, Janis, & Jones (1993) Home range size in mammals depends on habitat quality Home range size of fishers (Martes pennanti) is higher in the Rocky Mountains where habitat quality is lower Zielinski, Truex, Schmidt, Schlexer, Schmidt, & Barrett (2004) 140 E Forest 1 120 E Forest 2 Least chipmunks L Forest 1 100 L Forest 2 inhabit both forest and L Forest 3 sagebrush habitats in 80 the Laramie Range, 60 Abundance Wyoming, but 40 abundance is higher in 20 0 forest stands. 140 Sagebrush 1 120 Sagebrush 2 Sagebrush 4 100 80 60 40 Abundance 20 0 2004 2006 2008 2010 2012 2014 2016 Year Female-biased sexual size dimorphism is typical in most chipmunk species, including the least chipmunk (Tamias minimus). 65 60 55 50 45 Mass (g) 40 Body mass of least chipmunks live-trapped in 35 forest and sagebrush 30 habitats in the Laramie Females Males Females Males Range Wyoming 2006 - 2014 Forest Sagebrush Annual cycle January Hibernation October April Arousal Preparation for hibernation Breeding July We hypothesized that: 1. Male T. minimus individuals will have smaller home ranges than females. 2. Home range size differences between male and female chipmunks will be more pronounced in sagebrush (more extreme) habitats. 3. There will be less overlap of home ranges in sagebrush habitats. Study Area • 21 km E of Laramie in Medicine Bow National Forest. • Elevation ~2600 m. • Climate semi-arid continental. • 6 grids: 3 sagebrush and 3 forest. – Sagebrush species: Mountain big sagebrush, scattering Limber pine. – Forest species: Ponderosa pine, Limber pine, Lodgepole pine, Quaking aspen, Common juniper. Study Area S1 F3 S4 S2 F1 F2 Trapping procedures • Tomahawk live traps – (Model 102). • Baited with peanut butter, oatmeal, molasses, apples, and strawberries. • Left open during day (6:30AM-4:00PM). • Each grid trapped for 5 consecutive days. Check for PIT tag YES NO Anesthetized Animal released Sexed Weighed PIT tag inserted Blood collected Select individuals (n=32) were fitted with a radio-collar ATS model M140 0.75g Tracking conducted daily from Sept 7 to Oct 16, 2015 Sampling scheme S1 F1 S2 Forest trapping F2 Sagebrush trapping S4 Tracking F2 & S2 Tracking F1 F3 Tracking S1 8/24/15 8/31/15 9/7/15 9/14/15 9/21/15 9/28/15 10/5/15 10/12/15 10/19/15 Date Analytical methods Calculated Details Analysis Home range Size of home range (ha) Minimum convex for male and females by polygon (MCP) and habitat type Kernel utilization distribution (KUD) (Program R) Home range overlap KUD 50%, 75%, and 95% contours (Program R) Body mass Body mass (g) of male and Compare between females by habitat type sexes and habitats with ANOVA Sample sizes Habitat Males Females Forest 13 6 Sagebrush 7 6 300 Females 250 Males 200 150 100 Maximum distanceMaximum (m) 50 0 Forest Sagebrush Home range sizes of chipmunks based on MCP ranged from 0.59-1.1 ha Core areas (50% KUD) in forest coincided with hotspots of trapping, but less so in sagebrush. Home range size based on 50% contours with KUD were similar to MCP and larger with 75% and 95% contours. No differences between sexes or habitats. 8 Female forest Male forest 6 Females sagebrush Male sagebrush 4 Area (ha) Area 2 0 MCP100 KUD50 KUD75 KUD95 Core areas (50% KUD) of both sexes showed little overlap. This segregation persisted for females in the 95% contours. Males exhibited higher overlap with females and other males. There were no habitat differences in overlap. 0.30 Male-Male 0.25 Male-Female Female-Female 0.20 0.15 0.10 0.05 Home range overlap (proportion) overlap range Home 0.00 50% contour 95% contour Most animals caught in sagebrush moved to forest or wooded sections of their home range prior to hibernation. Two pairs hibernated together. Chipmunks entered hibernation at the end of September early October Animals entered S1 hibernation S2 S2 S1 as evident F1 from signal S2 Forest trapping attenuation F2 Sagebrush trapping(deep Tracking F2 & S2 S4 Tracking F1 underground) F3 Tracking S1 8/24/15 8/31/15 9/7/15 9/14/15 9/21/15 9/28/15 10/5/15 10/12/15 10/19/15 Date We found that: 1. Male T. minimus individuals had similar home ranges to females. Was body mass of males similar to females in 2015? 65 60 No. Although chipmunks 55 were heavier in 50 2015 45 (especially in Mass (g) the forest), sex 40 differences persisted. 35 AB BC BB CC 30 Females Males Females Males Forest Sagebrush 140 E Forest 1 120 E Forest 2 We found that: L Forest 1 100 L Forest 2 L Forest 3 1. Male T. minimus individuals80 had similar home ranges to females. 60 Abundance 2. Home range size differences40 between male and female chipmunks were 20not more pronounced in 0 sagebrush (more extreme)140 habitats. Sagebrush 1 120 Sagebrush 2 Sagebrush 4 But there were 100 fewer individuals 80 in sagebrush, 60 40 especially in Abundance Sagebrush grid 1 20 0 2004 2006 2008 2010 2012 2014 2016 Year We found that: 1. Male T. minimus individuals had similar home ranges to females. 2. 0.30Home range size differences between male and female chipmunksMale-Male were not more pronounced in 0.25 Male-Female sagebrushFemale-Female (more extreme) habitats. 3. 0.20There was similar overlap of home ranges in forest and sagebrush habitats. 0.15 0.10 But females 0.05exhibited intra- Home range overlap (proportion) overlap range Home 0.00sexual territoriality 50% contour 95% contour Group and intra-sexual territoriality (in which both sexes avoid/repel same-sex conspecifics) is common in sciurids. California ground squirrels (Otospermophilus beecheyi) Gunnison prairie dogs (Cynomys gunnisoni) White-tailed prairie dogs (Cynomys leucurus) Red squirrels (Tamiasciurus hudsonicus) Woodchucks (Marmota monax) Intra-sexual territoriality of females only is rare and merits further Eurasian red squirrels (Sciurus investigation vulgaris) Communal hibernation occurs in several sciurid species: Northern flying squirrels (Glaucomys sabrinus) Alaska marmot (Marmota broweri) Communal hibernation has not been documented in chipmunks before and merits further investigation Additionally, in the future: Chipmunks should be trapped in areas with continuous sagebrush habitats to determine if home range size and overlap in truly extreme environments would be more or less pronounced. Additionally, in the future: Genetic relatedness of chipmunks should be assessed in relation to home range overlap and communal hibernation. Effects of annual changes in resource availability on home range size and overlap should be investigated. Acknowledgements • Carolyn Eckrich, Jamie Crait, Adi Barocas, Kristina Harkins, Brady Godwin, Bobby Riotto • All the graduate and undergraduate volunteers • 2004-2015 Wildlife Ecology and Management Classes • Funding Sources WY Wildlife Foundation WY Governor’s Big Game License Coalition University of Wyoming College of Arts and Sciences University of Wyoming Science Posse University of Wyoming EPSCoR University of Wyoming NASA University of Wyoming Department of Zoology and Physiology University of Wyoming Research Office Questions?.