PowerPointPrsentation

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Pivotal question
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Basic questions of projects Influence of
meteorological factors, social structure,
chronobiology ?daily nestbox checks
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Comparison of different intervals daily,
weekly, every fortnight, monthly

• population size

• number of newly marked animals

• number of recaptured animals from previous year

• comparison between population estimate by JOLLY
  and empirical data

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Population estimate by JOLLY (MUEHLENBERG1993) Ba
sed on the capture-recapture method to estimate
the size of a population Pi (ai Zi/Ri ri)
ni/ri Pi population estimate on day i ni
total number of animals captured on day i ai
total number of animals released on day i (newly
marked ones and marked recaptured ones) Zi sum
of all animals marked before day i and recaptured
after day i not in the sample of day Ri sum
of all animals marked and released on day i
which were recaptured after day i Factor Zi/Ri
allows for population dynamics e.g. gains and
losses of individuals
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• Day i day of highest MNA
• minimum number of animals known to be
  alive
• (PETRUSEWICZ ANRDZEJEWSKI 1962,KREBS 1966)

• data of weekly nestbox checks

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Study area
Schluechtern (50 19 N 9 28E)
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• Study area
• low mountain range
• altitude 250-300 m
• mixed forest consisting of oak (Quercus robur,
  Q.petraea), common beech (Fagus sylvatica) and
  hornbeam (Carpinus betulus)

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• total of 185 nestboxes with 32 x 38 mm entrance
  holes
• two-dimensional arrays of nestboxes in 25 x 25
  m grids

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Individual marking
45621
transponder (12x2.12mm)
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• Methods
• 2002
• weekly nestbox checks with marking of all
  unmarked dormice after breeding season of
  hole-breeding passerines
• 2. daily nestbox checks with marking of all
  unmarked individuals from July 4 th until Aug.
  3rd 2002
• Daily scanning of (shut) nestboxes, opening and
  marking twice a week from Aug. 4th
• 2003 (and afterwards)
• Daily scanning of (shut) nestboxes opening
  and marking once a week

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Basis 375 marked individuals (from 2002) that
could be theoretically recaptured in 2003
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Statistics
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Statistics
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Statistics
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Statistics
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Statistics
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• Significant differences between...
• total number of individuals except daily vs
  weekly
• found individuals in except daily vs weekly
• number of missed individuals
• missed individuals in
• number of newly marked individuals except every
  fortnight vs monthly
• recaptures except weekly vs. every fortnight
• recaptures in except daily vs weekly, weekly vs
  every fortnight

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• Consequences
• Statements concerning for example
• population size
• death rates
• emigration/immigration
• would differ significantly using data based on
  fewer checks.

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Day of highest MNA August 8th 2003 85
individuals
JOLLY versus MNA Chi224.009 df 1 p lt
0.001 JOLLY versus daily checksChi2146.815 df
1 p lt 0.001 MNA 30,25 of total number of
individuals until Aug. 8th 37.44 of total
population size (281 individuals)
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Using the JOLLY estimate the population would be
underestimated 7-fold. Although gains and
losses are allowed for in the JOLLY model,
empirical data shows more dynamics among the
members of the population.
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