COMPETITION BETWEEN MULE AND WHITE- TAILED DEER METAPOPULATIONS IN NORTH-CENTRAL WASHINGTON E. O. Garon, Kris Hennings : Fish and Wildlife Dep., Univ. of Idaho, Moscow, ID 83844 Maureen Murphy, and Seve Judd: Fish and Wildlife Dep., Colville Confederaed Tribes, Nespelem, WA 9955 Copyrigh 2 E. O. Garon Overview Inroducion and review of compeiion conceps Measuremen of compeiion Apply hese ideas o compeiion beween mule and whie-ailed deer on Colville Indian Reservaion Fuure direcions Do whie-ailed ailed and mule deer compee? A few auhors have suggesed ha mule and whie-ailed deer compee when heir disribuions overlap. Wha evidence is here? How severe is he compeiion? Can we measure he effecs on he species populaions? Ecological Definiions (Birch 957): Resource compeiion occurs when a number of organisms (of he same or differen species) uilize common resources ha are in shor supply. Inerference compeiion occurs when he organisms seeking a resource harm one anoher in he process, even if he resource is no in shor supply. Inraspecific vs. inerspecific Inraspecific compeiion occurs beween members of he same species. Inerspecific compeiion occurs beween wo or more differen species. Mule and whie-ailed ailed deer poenially compee. Dies and habia used overlap subsanially - Marinka, C. J. 968 Inerspecific behavior and dispersion provides some evidence for inerspecific compeiion - Kramer, A. 973 Adapabiliy and diversiy of resource and habia use by deer makes proof of resource limiaion difficul.
Evidence for compeiion Of more han 3 papers published specifically on compeiion beween ungulae species none provide convincing evidence for compeiion. None provide measures of srengh or impac of compeiion Compeiion Beween Mule Deer and Elk Lindzey, e al. 997 reviewed over 5 published papers or repors and surveyed biologiss in he wesern saes and provinces: Unforunaely, we are no aware of sudies ha compare reproducion and survival in symparic mule deer and elk populaions. Such comparaive informaion would be essenial prior o drawing any inferences abou compeiive effecs of one species on he oher s populaion growh How would you measure compeiion? Inerspecific compeiion occurs when wo or more species experience depressed growh rae or equilibrium populaion level aribued o heir muual presence in an area. Emlem 973 Finie rae: Insananeous rae: r Growh Rae λ = N + N = ln λ Consan or Changing Growh Rae? 8 7 6 5 4 3 2 99 993 995 997 999 Changing Consan Inraspecific Compeiion Ricker Model: r a N r 2.5.5 -.5 - -.5-2 N 2
Inraspecific Compeiion Ricker Model: r a N Discree ime logisic growh Remarkably complex and rich behavior Rober May(974) demonsraed 3 paerns: Low r max = smooh logisic (s-shaped) Medium r max = cycles High r max = chaoic populaion changes Inerspecific Compeiion Added Ricker Model: r a N Ricker Model wih Inerspecific Compeiion (May 977): r a N bm Can we apply hese ideas o mule and whie-ailed ailed deer? Colville Indian Reservaion Colville Reservaion Deer Populaion Size 2 5 5 WT MD 983 985 987 989 99 993 995 997 999 Year 3
How could Easside deer numbers change so quickly? Change in numbers due o more han birh and deah Deer move around in response o huning, environmenal condiions and ineracions Change = + birhs + immigrans - deahs emigrans These are METAPOPULATIONS Inerspecific Compeiion Added Ricker Model: r a N May s Model wih Inerspecific Compeiion (May 977): r a N bm Inraspecific Compeiion Whie-Tails Inraspecific Compeiion WT Growh Rae - 5 5 2 WT Populaion Size WT Regression of r on N for whie ails: r =.99 -.956 N for N in housands n=2 r =.73 F, =.4 P=.7 Densiy-dependen Effecs Evaluaing inraspecific compeiion like his has been reaed as esing for densiy-dependen effecs wihin populaions Eberhard (97), in a famous paper in Ecology, demonsraed ha you can easily ge a high negaive correlaion coefficien from a random number sequence because N is in denominaor of r as well as being he predicor. Densiy-dependen Effecs Dennis and Taper (994) developed a Parameric Boosrap Likelihood Raio es of densiy dependence in census daa: Applying his es o he -es for significance of he slope of he regression for whie-ails shows = -3.338 P<.5 4
Inraspecific Compeiion in Mule Deer Mule Deer Effecs on WT Regression of r on N for mule deer: r =.34 -.989 N for N in housands n=2 r =.86 = -5.28 P<. by PBLR WT Growh Rae - 5 5 2 Mule Deer Numbers Inerspecific Compeiive Effecs on Whie Tails by Mule Deer Regression of r on M for mule deer: r =.29 -.945 M for M in housands n=2 r =.7 F, =.3 P=.9 Mule Deer Growh Rae Effec of Whie-ails on Mule Deer.5 5 5 2 -.5 - Whie-ailed Deer Populaion Size Inerspecific Compeiive Effecs on Mule Deer by Whie Tails Regression of r on N for mule deer: r =.552 -.54 N for N in housands n=2 r =.44 F, = 2.44 P=.49 Toal Compeiive Effecs Whie-ail Model: r =.47.48WT. 44 M Mule Deer Model: r =.3.6WT. 79M 5
Whie-ail ail Growh Model R=.82 R 2 =.66 F, =.4 P =.7 Mule Deer Growh Model R=.86 R 2 =.74 F 2,9 =.37 P =.2 Model Building Approach Since we have no (canno) assign levels of predicors (mule and whie-ail numbers) a random, many would quesion he applicaion of inferenial saisics and hypohesis esing o hese daa. An alernaive approach is o rea his as a model building effor and apply informaion heoreic ools o selecing a parsimonious model. Model Building Approach Using Akaike s Informaion Crierion AIC DelaWhieTails/Year = WT + MD 9.3 DelaWhieTails/Year = WT 8.8 DelaMuleDeer/Year = WT + MD 34. DelaMuleDeer/Year = MD 9.3 Elk Populaion Growh Mule Deer Produciviy and Elk Populaion Size During he las 2 years elk populaions have increased dramaically in many areas. Experimenal sudies a Sarkey Experimenal Fores have shown ha mule deer avoid areas occupied by elk Elk on he Colville Reservaion increased from abou animals in 98 o almos 6 in 2. 6
Whie ailed Deer Produciviy and Elk Wha nex? Sochasic model Simulaion o explore behavior fully Apply mehods of Subash Lele and Mark Taper ha model im-/e-migraion Apply o elk-deer compeiion and ohers 7