Factors affecting growth parameters of White Stork nestlings in eastern Algeria
Résumé
Survival and reproduction of young can be affected
by growth parameters. It is thus important to estimate
intraspecific growth rate variability and
environmental factors affecting growth to better understand
the dynamics of populations and the potential impacts of
environmental changes. Growth parameters of White Stork
(Ciconia ciconia) nestlings were estimated in eastern Algeria,
in the southern part of the species’ range. A total of
2,756 measurements of 65 nestlings from 18 nests were
taken for body mass, and tarsus, wing and bill lengths.
Individual growth data were used to investigate the effects
of nest occupation date, laying and hatching dates, clutch
size, number of hatchlings, productivity, hatching order,
and brood reduction on nestling growth patterns. Body
mass and bill length growth rates were lower in the studied
population than in a more northerly White Stork population.
This supports the hypothesis of a geographic variation
in intraspecific growth parameters. Chicks from nests occupied
early reached higher asymptotic body mass but
tended to grow more slowly. However, chicks from late
arriving birds compensated for the difference in body mass and wing length by higher growth rates. Wing length was
significantly affected by asynchrony and hatching order.
Last hatched chicks had larger asymptotic wing lengths,
lower wing growth rates and longer growth periods. Wings
of nestlings from highly asynchronous broods grew faster
but took more time to attain the inflection point. Brood
reduction had a negative effect on nestling bill length at
hatching. Chicks from nests with little brood reduction had
a longer bill at hatching than nestlings from nests with high
brood reduction.