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Intl. J. of Super Species Research 2012, Vol.2, No.1, 1
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http://ijssr.sophiapublisher.com
3
3 Results
A total of 132 birds (including 13 recaptures) from 20
different species were caught and examined for
feather mites. Without considering recaptured birds,
blackcap, Sardinian warbler, chiffchaff, willow
warbler and house sparrow were the most commonly
captured birds (Table 1), contributing to over 77% of
the birds caught. Table 1 shows mite prevalence,
average mite numbers and the number of birds caught
per species. Most species had N<10 and were not used
for analysis and although chiffchaff, willow warbler,
and house sparrow were included in the analysis, the
data should be treated with a degree of caution since
samples size is small.
The four most common species and showed a
significant difference in mite abundances (Kruskal
Wallis
2
=31.193, df=3, p<0.001) as shown in Figure 1.
Blackcaps had the highest average mite abundances,
followed by house sparrows, Sardinian warblers and
willow warblers. Both Sardinian and willow warblers
were characterized by relatively low mite abundances
but had a few outliers.
Figure 1 Feather mite abundances for the four most common species
There are no significant differences in mite abundance
between males and females in blackcaps (Kruskal Wallis
2
=0.38, df=1, p=0.538); house sparrow (Kruskal Wallis
2
=0.046, df=1, p=0.829); Sardinian warbler (Kruskal
Wallis
2
= 0.011, df=1, p=0.916) and willow warbler
(Kruskal Wallis
2
= 0.327, df=1, p=0.568).
No significant differences were found in mite
abundance between juvenile and adults blackcap
(Kruskal Wallis
2
=0.012, df=1, p=0.912) and
Sardinian warbler (Kruskal Wallis
2
=0.359, df=1,
p=0.549). It was not possible to analyse if age has an
effect on mite abundances of willow warblers and
house sparrows, as it was impossible to determine
ages based on moulting patterns.
A summary of Spearman’s rank correlations of feather
mites to body condition measures is given in Table 2.
There were no significant correlations between feather
mites with body conditions (fat, pectoral muscles and
weight) at the p=0.05 significance level, except in
Sardinian warbler where mites were positively
correlated to fat levels (Spearman’s ρ=0.779, df=14,
p<0.001); and in blackcap mites were marginally
positively correlated to weight (Spearman’s ρ=0.296,
df=35, p=0.085).
Figure 2 Feather mite distributions across different areas of the
wing for passerine species
The occurrence of feather mites on wing regions (P1-3,
P4-6, P7-10, secondaries and random distribution)
varied significantly between the 4 species (Kruskal
Wallis
2
=12.388, df=3, p=0.006). As shown in Figure 2,
mites on blackcap were mainly found on P7-10
(Fishers Exact test value =20.215, p<0.001) and mites
on house sparrows were concentrated on P4-6 (Fishers
Exact test value = 6.223, p<0.045).
There was significant reductions in the numbers of
mites on the wings for birds roosted overnight
(Fisher’s exact test value=6.223, p=0.045), indicating
that there were significant daily changes in abundance
on the wings and that these were greater than could be
expected by sampling error alone.