TY - JOUR
T1 - Long-term trends in survival of a declining population:the case of the little owl (Athene noctua) in the Netherlands
AU - Le Gouar, P.J.M.
AU - Schekkerman, H.
AU - Van der Jeugd, H.P.
AU - Boele, A.
AU - van Harxen, R.
AU - Fuchs, P.
AU - Stroeken, P.
AU - Van Noordwijk, A.J.
N1 - Reporting year: 2011
Metis note: 4933; WAG; AnE; VT
PY - 2011
Y1 - 2011
N2 - The little owl (Athene noctua) has declined significantly
in many parts of Europe, including the Netherlands.
To understand the demographic mechanisms
underlying their decline, we analysed all available Dutch
little owl ringing data. The data set spanned 35 years, and
included more than 24,000 ringed owls, allowing detailed
estimation of survival rates through multi-state capture–
recapture modelling taking dispersal into account. We
investigated geographical and temporal variation in agespecific
survival rates and linked annual survival estimates to
population growth rate in corresponding years, as well as to
environmental covariates. The best model for estimating
survival assumed time effects on both juvenile and adult
survival rates, with average annual survival estimated at
0.258 (SE = 0.047) and 0.753 (SE = 0.019), respectively.
Juvenile survival rates decreased with time whereas adult
survival rates fluctuated regularly among years, low survival
occurring about every 4 years. Years when the population
declined were associated with low juvenile survival. More
than 60% of the variation in juvenile survival was explained
by the increase in road traffic intensity or in average temperature
in spring, but these correlations rather reflect a
gradual decrease in juvenile survival coinciding with longterm
global change than direct causal effects. Surprisingly,
vole dynamics did not explain the cyclic dynamics of adult
survival rate. Instead, dry and cold years led to low adult
survival rates. Low juvenile survival rates, that limit
recruitment of first-year breeders, and the regular occurrence
of years with poor adult survival, were the most important
determinants of the population decline of the little owl.
AB - The little owl (Athene noctua) has declined significantly
in many parts of Europe, including the Netherlands.
To understand the demographic mechanisms
underlying their decline, we analysed all available Dutch
little owl ringing data. The data set spanned 35 years, and
included more than 24,000 ringed owls, allowing detailed
estimation of survival rates through multi-state capture–
recapture modelling taking dispersal into account. We
investigated geographical and temporal variation in agespecific
survival rates and linked annual survival estimates to
population growth rate in corresponding years, as well as to
environmental covariates. The best model for estimating
survival assumed time effects on both juvenile and adult
survival rates, with average annual survival estimated at
0.258 (SE = 0.047) and 0.753 (SE = 0.019), respectively.
Juvenile survival rates decreased with time whereas adult
survival rates fluctuated regularly among years, low survival
occurring about every 4 years. Years when the population
declined were associated with low juvenile survival. More
than 60% of the variation in juvenile survival was explained
by the increase in road traffic intensity or in average temperature
in spring, but these correlations rather reflect a
gradual decrease in juvenile survival coinciding with longterm
global change than direct causal effects. Surprisingly,
vole dynamics did not explain the cyclic dynamics of adult
survival rate. Instead, dry and cold years led to low adult
survival rates. Low juvenile survival rates, that limit
recruitment of first-year breeders, and the regular occurrence
of years with poor adult survival, were the most important
determinants of the population decline of the little owl.
U2 - 10.1007/s00442-010-1868-x
DO - 10.1007/s00442-010-1868-x
M3 - Article
SN - 0029-8549
VL - 166
SP - 369
EP - 379
JO - Oecologia
JF - Oecologia
IS - 2
ER -