The form of the growth curve sketched by a population increasing from low numbers is determined by the relationship between the population and the dynamics of its resources G. Caughley & A.R.E. Sinclair

Population Ecology Revisited How do births, deaths, immigration, & emigration affect wildlife populations? What affects births, deaths, immigration, & emigration? What are demographic characteristics? What is the difference between exponential & logistic population growth? What is Aldo’s model?

Population Ecology Revisited What is carrying capacity? What are patterns of abundance and what controls them? What is metapopulation and how does it relate to wildlife population dynamics? Population management Who cares?

Population Ecology Revisited What is a population? Why not deal with individuals? (U.S Fish & Wildlife Service)

Population Ecology Revisited N = B + I – D – E (demographic characteristics) N t+1 = N t + B t + I t – D t – E t  N Effects of: Harvest Restocking Habitat Weather Other organisms Population Size Births Deaths Immigration Emigration ♂:♀ Juvenile:Adult

Population Ecology Revisited Population growth without resource limitation –Exponential N t = N 0 e rt dN/dt =  N/  t = rN –Assumes no I & E or I = E –Assumes no structure –r »Instantaneous rate of increase, intrinsic rate of increase, Malthusian parameter, or per capita rate of increase »b - d »Units: ind/(ind*time) »Based on 0 N Time AB N dN/dt AB Biotic Potential C

Population Ecology: The Basics Population growth with resource limitation (in relation to conditions) –Logistic growth N t = K/(1 + [{K - N 0 }/N 0 ]e -rt ) dN/dt = rN(1 - [N/K]) –Assumes no I & E or I = E –Assumes no structure –K = carrying capacity »Max. # the environment can support »Assumes constant K »Can change with time & space »K = N? »K > N? »K < N? »K = ∞? –Density-dependence N dN/dt N Time Accelerating Phase K Inflection Point (½ K) Decelerating Phase Inflection Point (½ K) K

Population Ecology Revisited Population growth with resource limitation (in relation to conditions) –Logistic growth N t = K/(1 + [{K - N 0 }/N 0 ]e -rt ) dN/dt = rN(1 - [N/K]) –r v. dN/dt –Unused portion of carrying capacity »(1 - [N/K]) »N = 2, K = 100 → 0.98 »N = 98, K = 100 → 0.02 N dN/dt N Time Accelerating Phase K Inflection Point (½ K) Decelerating Phase Inflection Point (½ K) K

Population Ecology Revisited What is this thing called Carrying Capacity? –Ecologically-based K-carrying capacity (KCC) –Socio-economically-based I-carrying capacity (ICC) Optimum carrying capacity (OCC) Minimum-impact carrying capacity (MCC) –Animals must be removed N Time MCC KCC ICC (½ K) OCC

Population Ecology Revisited Aldo Leopold’s Population Model –Decimating factors –Welfare factors –Other possibilities? Exposure Space Harvest = removal –The limiting factor (link)? –Abnormal mortality –Influences Land-uses Weather Fire N Time K Inflection Point (½ K) Hunting (Harvest) Diseases & Parasites Accidents Starvation Food Cover Water Special Factors Welfare Factors Predation Environmental Resistance Decimating Factors Biotic Potential

Population Ecology Revisited Other patterns of abundance –Density-dependent v. density-independent factors –Causes? N Time N N D BA N C K K K

Population Ecology Revisited Metapopulations –Groups of local populations Subpopulations or demes Size, quality, connectivity, & distance (I & E are important) –Island Biogeography & Conservation Biology »Matrix

Population Ecology Revisited Minimum viable populations (MVP) –National Forest Management Act of 1976 –Species- & site-specific –50/500 rule USDA photo by: Bob Nichols

Population Ecology Revisited Minimum viable populations (MVP) –Shaffer (1981) Need for performance criteria 99% chance of surviving for 1000 years despite stochastic events –Genetic stochasticity –Environmental stochasticity –Natural catastrophes –Demographic stochasticity »BBDBBD v. DDBBBB –Importance of individuals Florida panther (U.S Fish & Wildlife Service)

Population Ecology Revisited Effects of sex & age structure on population growth? –Mating habits –Differential vulnerability Population Size Births Deaths Immigration Emigration ♂:♀ Juvenile:Adult

Population Ecology Revisited Population Management –Lethal methods Hunting, trapping, fishing, & collecting (recreational) –Harvest management »Yield »Diminishing returns »Compensation »History, trial & error, and Adaptive Harvest Management Culling, sharp-shooting, trap/collect & euthanize, addle & oil, poisoning, etc. Increase other mortality factors (conditions) –Diseases, predators, etc.

Population Ecology Revisited Population Management –Non-lethal methods Restocking –Captive breeding programs Trap & transfer (translocation) Sterilization & contraception Repellents Habitat manipulation –Survival & reproduction –Use

Population Ecology Revisited So what!