Density dependence and stochastic variation in a newly established population of a smal songbird

TY - JOUR

T1 - Density dependence and stochastic variation in a newly established population of a smal songbird

AU - Saether, B-E.

AU - Engen, S.

AU - Lande, R.

AU - Both, C.

AU - Visser, M.E.

N1 - Reporting year: 2002 Metis note: 3094; CTE; PVD ; AnE; file:///L:/Endnotedatabases/NIOOPUB/pdfs/Pdfs2002/Saether_ea_3094.pdf

PY - 2002

Y1 - 2002

N2 - Models describing fluctuations in population size should include both density dependence and stochastic effects. We examine the relative contribution of variation in parameters of the expected dynamics as well as demographic and environmental stochasticity to fluctuations in a population of a small passerine bird, the pied flycatcher, that was newly established in a Dutch study area. Using the theta-logistic model of density regulation, we demonstrate that the estimated quasi-stationary distribution including demographic stochasticity is close to the stationary distribution ignoring demographic stochasticity, indicating a long expected time to extinction. We also show that the variance in the estimated quasi-stationary distribution is especially sensitive to variation in the density regulation function. Reliable population projections must therefore account for uncertainties in parameter estimates which we do by using the population prediction interval (PPI). After 2 years the width of the 90% PPI was already larger than the corresponding estimated range of variation in the quasi-stationary distribution. More precise prediction of future population size than can be derived from the quasi-stationary distribution could only be made for a time span less than about five years.

AB - Models describing fluctuations in population size should include both density dependence and stochastic effects. We examine the relative contribution of variation in parameters of the expected dynamics as well as demographic and environmental stochasticity to fluctuations in a population of a small passerine bird, the pied flycatcher, that was newly established in a Dutch study area. Using the theta-logistic model of density regulation, we demonstrate that the estimated quasi-stationary distribution including demographic stochasticity is close to the stationary distribution ignoring demographic stochasticity, indicating a long expected time to extinction. We also show that the variance in the estimated quasi-stationary distribution is especially sensitive to variation in the density regulation function. Reliable population projections must therefore account for uncertainties in parameter estimates which we do by using the population prediction interval (PPI). After 2 years the width of the 90% PPI was already larger than the corresponding estimated range of variation in the quasi-stationary distribution. More precise prediction of future population size than can be derived from the quasi-stationary distribution could only be made for a time span less than about five years.

U2 - 10.1034/j.1600-0706.2002.990214.x

DO - 10.1034/j.1600-0706.2002.990214.x

M3 - Article

SN - 0030-1299

VL - 99

SP - 331

EP - 337

JO - Oikos

JF - Oikos

IS - 2

ER -