Vigilance in African mammalian carnivoresWiline TrouilloudPhoto: Wiline TrouilloudBackground• Undergrad: McGill University Dr. Kramer’s lab• Ph.D.: MSUDr. Holekamp’s labPhoto: Wiline TrouilloudPhoto: Jaime Tanner• Cryptic behaviors:Ex: Slow down; freeze; body decorations• Habitat selection:Ex: Under cover; in the open; dark water• Vigilance• Join groups (conspecifics or polyspecifics)Antipredator behaviors:1. Avoid detectionAntipredator behaviors:2. Once detected• Warn predator that it’s detected• Alarm others• Flight (run)• Fight (spray, etc) • Escape by losing body parts• Mob predator• Play deadVigilance is a behavior that increases the probability of detecting a stimulusPhoto: Wiline TrouilloudComponents of vigilance• Duration of head raise (in sec)• Rate of head raises (#/min)= Percent time spent vigilant• Today: only rate1.2.Foraging: Tradeoff between vigilance and food intakeClassical studiesPhoto: Wiline TrouilloudUnderlying theory• Behavior should optimize fitness• Fitness = related to birth/deathHere, we’re assessing fitness by looking at growth (i.e. food intake; rest; parental care)Nothing on carnivores!Photo: Wiline TrouilloudOutline of research• Comparative study on mammalian carnivores• Case study of spotted hyenas– Background on the project – Natural history of the spotted hyena– Description of vigilance in hyenas– Experiments (playbacks) in hyenasComparative study of vigilance in African carnivoresPhoto: Wiline TrouilloudPhoto: Wiline TrouilloudPhoto: Wiline TrouilloudBackground on study• Need to understand behavior to protect speciesesp. anti-predator behavior• Predictions:– Species with larger body sizes will have lower rates of vigilance– Species more social will have lower rates of vigilanceMethodology• Context: feeding and resting• Video + independent variables• Sympatric species• Range of body sizes to test predictions50 12511460.324Body weight (kg)Photo: Wiline TrouilloudPhoto: Wiline TrouilloudPhoto: Wiline TrouilloudPhoto: Kay Holekamp1.519060Rate of head raises (#/min)0246810Vigilance while feedingBody weightDwarf mgLionMLionFHyenaBand mgJackalWild dogCheet. Leop.Sociality Index0123456Rate of head raises (#/min)0246810121416Vigilance while feedingRegression:R2=0.26 F1,216 = 5.92P=0.01Rate of vigilance (#/min)0.00.20.40.60.81.01.2Vigilance while restingBody weightCheetah Hyena Lion F Lion MConclusions• Much lower rate of vigilance while resting(what would you predict for duration?)• Decrease rate of vigilance with increasing body weight• When feeding: social species have higher rate of vigilance• Conflicting factors: phylogeny, habitat, age, # predatorsNow one species more in depthSpotted hyenas(Crocuta crocuta)Why hyenas?Photo: Wiline TrouilloudPhoto: Wiline TrouilloudSocial clan (up to 100 individuals)Photo: Wiline TrouilloudKill sequence(Predator~60kg; Prey~180kg)Ph tJS ithIntense intraspecific competitionPhoto: Kay HolekampIntense interspecific competitionPhoto: Wiline TrouilloudHyena ProjectDr. Holekamp’s labVigilance of a social carnivore• Description of vigilance in a social carnivore• Variation with rank, age, contexts• Group size effect?Photo: Holekamp LabPredictions• Should hyenas be more vigilant when young or as adults? Should hyena mothers be more worried about cubs when really young or when older?• Predictions: – Hyenas will be most vigilant when they are the most at risk (i.e. when being weaned)– Mothers will be most vigilant when cubs are youngAge (months)020406080100120# head raises / min0123456Effects of age on the rate of vigilance for hyenas feeding on killsF1,36 =20.9 r2=0.37 P<0.001Age (in months)5 1015202530354045# head ups / min0.00.20.40.60.81.01.21.4Photo: Katy CaliffEffect of age on rate of vigilance for hyenas restingF2,31=8.47; r2=0.35; P=0.001Effect of age of litter on rate of vigilancefor mothers nursingAge (in months) of the litter being nursed0 2 4 6 8 10121416Adult females' rates of vigilance while nursing a litter (#/min)0.00.51.01.52.02.53.03.5N=22 R2= 0.317 P<0.001Photo: Kay HolekampRelationship between lions and hyenasPlayback experiments of lion roars to hyenas of different age and rankHypothesis:Low rank and low prey availability will lead to an increased risk taking, esp. in newly weaned hyenasMethodologyPhoto: Wiline Trouilloud100 mAge (in months)0 20 40 60 80 100 120 140 160 180Proportion of time spent fleeing away from speakers-20020406080100N=25 R=0.465 P=0.025Effect of age on the proportion of time spent fleeing away from speakers following a lion roar playback01020304050607080cub subadult adultRate of movement (m/min)RoarWahoo*****45851311Rate of movement following playbackProportion time spent approaching, fleeing or orienting towards the speakers after roar playback0102030405060708090100class 3 class 4 class 5Percent time spent (%)ApproachingFleeingOrientingNSNSP=0.064813Cubs Subadults AdultsHuman disturbance and its effects on antipredator behaviorCompare clan with low disturbance to clan with high disturbancePhotos: JoeKolowskiTalek ClanMara River Clan10 0 10 20 KilometersNEWSTalek Territory BoundaryMara River Territory BoundaryReserve BorderMajor RiversKENYATalek RiverMara RiverFigure 1. Map of Masai Mara National Reserve and estimated territory boundaries of the Mara River and Talek spotted hyena clans. Study populations Study 1:Observations of vigilance in all 3 contexts (feeding, resting, nursing) for both clansStudy 2: Playback experiments of cow bells(control sound: church bells)Cow bellsChurch bellsConclusions• Young hyenas less vigilant than adults (both when resting and when feeding)• Mothers most vigilant when nursing young cubs• Young cubs show stronger reactions to lion roars than adults (spend more time fleeing, flee faster)Acknowledgements• Funding: AAUW International fellowship, Barnett-Rosenberg fellowship, Graduate Women in Sciences Eloise-Gerry grant, EEBB, Department of Zoology, College of Natural Sciences, NSF to KEH.• Audrey DeRose-Wilson and Aimee Cokayne in the field• Dr. Holekamp and the Holekamp labAverage duration of head raises (in sec)02468101214Vigilance while feedingDwarf mgLionMLionFHyenaBand mgJackalWild dogCheet. Leop.Body weightBody weightX Datacheetah hyena lion F lion MDuration of head raises (in sec)01020304050Vigilance while