Agriculture Reference
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Non-parametric Spearman correlation tests were used to determine relationships
between bird and bat species richness and abundance, habitat characteristics and
landscape variables. The dependant variables for birds consisted of the average
number of species and individuals (resident species and forest species) observed
per point count in each habitat type per locality. For bats, dependant variables were
the number of species and individuals (all bats, fruit bats, forest bats, cave bats) per
mist-net-line. We corrected for effort by dividing the number of species and indi-
viduals by the number of net-nights. The latter was calculated by multiplying the
number of nets in a mist-net-line by the number of nights these nets were open. As
all nets were equal in size, no correction of net length or area was needed. For
comparisons with other studies: one net-night in our study is equivalent to 10 net-
meter-nights, or 120 net-meter-hours (10 m * 12 hours of nocturnal netting time) or
32 net-square-meter-nights (3.2 m * 10 m). All statistical analyses were performed
using SPSS version 13 for Windows (SPSS Inc. 2004).
16.3 Results
In 118 point counts we recorded a total of 1,093 individual birds belonging to 58
resident bird species (Table 16.2). Eleven of these were endemic to the Philippines
(19 percent) and 15 (26 percent) were forest species. One species, Anas luzonica,
was listed as threatened (vulnerable) on the IUCN red list (IUCN 2006). A total of
409 individual bats belonging to 16 species were captured in 34 mist-net-lines with
a total effort of 376 net-nights. Five bat species were endemic to the Philippines (31
percent) and one species was listed as vulnerable (IUCN 2006): Haplonycteris
fischeri . Seven species belonged to the Pteropodidae, the fruit bats.
We observed 38 resident bird species in Gmelina forest of which ten were forest
birds (26 percent) and seven were endemic species (18 percent). In homegardens we
observed 27 resident bird species including five forest birds (18 percent) and three
endemics (11 percent). The highest bird species richness was recorded for shrub-
land where we observed 47 resident bird species of which six were forest species (13
percent) and six endemic species (13 percent). Gmelina forest and homegardens
shared 71 percent of resident bird species (Sørensen similarity index), Gmelina for-
est and shrub-land 68 percent and homegardens and shrub-land 62 percent.
The most common species in Gmelina forest was Pycnonotus goiavier (mean
0.978 per point count). In homegardens, the most common species was Passer
montanus (mean 5.694 per point count), a species introduced to the Philippines
more than 100 years ago and nowadays well established on all inhabited Philippine
islands (Dickinson et al. 1991). Passer montanus was also the most common spe-
cies in shrub-land albeit with a lower density than in homegardens (mean 1.417 per
point count). All species and their relative abundance are presented in Table 16.3.
In Gmelina forest, seven forest bird species occurred that were absent in the
other two habitat types. Among these were four species endemic to the
Philippines: Cuculus pectoralis, Ixos philippinus (Photo16.3), Rhipidura cyani-
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