Ecology & Physiology• Cost and Benefits of Sociality• Environmental Constraints• Environmental Influences on BehaviorPhysiology (Hormones) and BehaviorEnvironmental Influences on PhysiologyStressors in the Lives of Free-Living Spotted Hyenas (Crocuta crocuta)Page Van MeterDepartment of ZoologyStress Hormones: Glucocorticoids (GC)• Released from adrenal glands• Part of the “flight or flight” responseGlucocorticoids:• Acute benefits– Mobilizes energy reserves– Restricts non-essential processes• Chronic costs– Compromises cardiovasculature– Pathogenic immune responseFriend and Foe?GCsGlucocorticoids:• Factors that influence GC levels:– Aspects of life historyK. HolekampGlucocorticoids:• Factors that influence GC levels:– Aspects of life history– SocialityGlucocorticoids:• Factors that influence GC levels:– Aspects of life history– Sociality– EcologyGlucocorticoids:• Sampling and Measuring techniques:– Blood samplingGlucocorticoids:• Measuring and sampling techniques:– Non-invasive samplingGlucocorticoids:Study Objective• To asses naturally occurring stressors in the lives of a large carnivore, the spotted hyena.Study Structure• Long-term data from a single, stable clan• Cross sectional analysis of multiple clans• Non-invasive fecal hormone sampling (fGC)Hyena ProjectBackgroundMASAI MARAHyena ProjectBackgroundTalekMasai Mara Spotted Hyena Project• Data collection from the Talek clan include:– 12 years of opportunistic fecal sampling– Demographics– Ecology– BehaviorBackground• Spotted hyenas:– Live in large social groups (50-80 individuals)– Fission-fusion society– Linear dominance hierarchyBackgroundMasai Mara Spotted Hyena ProjectK. HolekampMethods:Data CollectionRIAPossible Stressors in the Lives of Spotted HyenasH. 1 Inter-specific CompetitionH. 2 Intra-specific CompetitionH. 3 Social InstabilityH. 4 Anthropogenic DisturbanceHypothesis #1Inter-specific Competition• Lions (Panthera leo):– Compete directly with hyenas for prey and access to kills– Leading cause of mortality in Talek hyenas (Watts, in press)A. Engh• Rank and glucocorticoids:– Dogma: subordination is stressfulHypothesis #2Intra-specific CompetitionCarnivores (Creel, 2005)Vs.Old-world primates (Abbott, 2003)• Spotted hyenas:– Rank determines access to food– Fierce competition for access to kills (Holekamp, 1993)Hypothesis #2Intra-specific CompetitionK. HolekampNo relationship between rank and fGCs(Dloniak, 2003; Goymann, 2003)• Changes in Aggression:–RateHypothesis #2Intra-specific Competition# aggressions at killtime observed# hyenas present//• In a stable social system what happens when things become unstable? (baboons; Engh, 2006, and hyenas; Goymann, 2001)• 2 incidents promoting social instability:– Death of alpha late May 1999 – Fission of clanHypothesis #3Social Instability1993 20051999 2001• Few studies of anthropogenic disturbance on animal physiologyHypothesis #4Anthropogenic DisturbanceJ. Kolowski K. TheisHypothesis #4Anthropogenic Disturbance• Talek clan (Boydston, 2003; Kolowski, 2006; and Watts, in press)– Human density steadily increases– Livestock grazing affects Talek female behaviors– Humans are a significant source of mortalityH. Watts• Models are separated by sex and reproductive state:– Immigrant males, N=232 samples– Non-pregnant females, N=531 samples– Pregnant females, N=84 samples• Significance:– P < 0.05, significant– P < 0.1, trendStatisticsP = 0.039P = 0.060P = 0.093Anthropogenic DisturbanceP = 0.022N/SN/SImmigrant MalesP = 0.014N/SN/SNon-Pregnant FemalesN/SN/SN/SPregnant FemalesSocial InstabilityIntra-specific CompetitionInter-specific CompetitionHypothesisResults:Unstable StableFecal Glucocorticoids (ng/g feces)050100150200250Results:Social InstabilityUnstable StableFecal Glucocorticoids (ng/g feces)050100150200250fGC = 84.76 + Stability(-1.24), F(1,194) = 5.32, p = .022fGC = 69.31 + Stability(-1.17), F(1,496) = 6.14, p = .014Immigrant Males Non-Pregnant FemalesResults:Anthropogenic Disturbance 01002003004005006001992199419951997199819992001200220032005Time (Anthropogenic Disturbance)fGC (ng/g feces)Immigrant Males020040060080010001992199419951997199819992001200220032005Time (Anthropogenic Disturbance)fGC (ng/g feces)Non-Pregnant FemaleslogfGC = 50.78 + time(1.03), F(1,160) = 2.86, p = .093logfGC = 54.14 + time(1.01), F(1,129) = 3.61, p = .060Results:Anthropogenic Disturbance 020040060080010001992199419951997199819992001200220032005Time (Anthropogenic Disturbance)fGC (ng/g feces)Pregnant FemaleslogfGC = 91.12 + time(1.03), F(1,79) = 4.86, p = .039Initial Conclusions• Lion encounters do not predict fGC• Variation in aggression over food is not related to fGC• Instability of social hierarchy increases fGCin immigrant males and non-pregnant females• Trend of increasing fGC over time which may be related to increasing human disturbance…Hyena ProjectBackgroundMASAI MARAAMBOSELIHyena ProjectBackgroundTalek ClanMara River Clan• Amboseli: Oct. 2003-Jul. 2005• Masai Mara–Talek: Oct. 2003-Jul. 2005–Mara River: Sept. 2002-Oct. 2004Cross Clan ComparisonMasai MaragrasslandsgrasslandsgrasslandsEcologyLowHighLowHuman Density0.37/km21.00/km2Talek1.00/km21.02/km2Hyena density0.37/km20.05/km2Lion densityMara RiverAmboseliMasai MaraLOWHIGHLOW(Human densityLOWHIGHLOWfGCsHIGHHIGHLOWfGCs0.37/km21.00/km2Talek1.00/km21.02/km2Hyena density0.37/km20.05/km2Lion densityMara RiverAmboseliPREDICTIONSAmboseli Talek Mara RiverFecal Glucocorticoids (ng/g)050100150200250abbN=82 N=24N=69Cross Clan ComparisonLowHighLowHumansHighHighLowLionsfGC PredictionsConclusions• Longitudinal study of Talek:– Social instability and increasing human density increase fGC• Cross clan comparison:– Human density, rather than lion density, elevates fGCs in hyena populations• Conservation implications to a keystone speciesQuestions?:History of lions and hyenas in Amboseli National Park1960 2002~ 40 lions~ 50 hyenaslionsextirpated~30 lions~ 300 hyenas1989