11. Avian Communities in Temperate Rainforests
231
covered nests, including those nesting in tree cavities as well as in other
holes or building dome nests; 3) understory users, including those that
nest or forage principally in the understory «3 m or so); some birds were
assigned to an "understory" guild on the basis of common foraging
and/or nesting locations, but males of these species often sing from the
canopy (e.g., Passerina cyanea, Ixoreus varius, Turdus migratorius, and
Catharus guttatus, to name a few in North America, and Turdus falklandii
in Chile); 4) aerial feeders, including species that often feed on the wing,
either hawking or hover-gleaning insects; 5) canopy seed predators,
including species known to extract seeds from fruits or cones for a major
portion of their diet; 6) leaf-gleaners, including insectivorous species that
feed while moving along or between branches. These categories are a first
approximation, pending an increased information base, especially for
Chile. Many of the guilds used in this chapter are based on the location of
a particular resource, because of our interest in what might happen if the
availability of such resources were altered (Willson, De Santo, Sabag, &
Armesto, 1994). Number 2 above is a clear exception, in that it depends
in part on particular types of constructed nests, rather than a resource.
Nevertheless, we include it, because nesting habits can have a profound
effect on patterns of reproductive success, which in turn can influence
species presence and abundance.
In this preliminary assessment, a given species can belong to more than
one of these guilds, and the sum of all the guilds need not be 100% of the
community. The guild assignment of most midwestern species can be
obtained from Willson (1974), and those for Alaska and adjacent Canada
are from Flack (1976) and Willson (unpublished). For Chiloe, some guild
assignments are shown in Willson, De Santo, Sabag, and Armesto (1994);
in addition, the canopy seed predators are Enicognathus leptorhynchus,
Columba araucana, and Phrygilus patagonicus; aerial feeders include
Elaenia albiceps, Pyrope pyrope, Colorhamphus parvirostris, and
Tachycineta leucopyga (both Elaenia and Pyrope also consume much
fruit); and leaf-gleaners include Anairetes parulus, Colorhamphus parvirostris, Eugralla paradoxa, Scytalopus magellanicus, and Sylviorthorhynchus desmursii.
Statistical Methods
Direct comparisons of diversity, abundance, and guild structure for our
1992 data for Chile and Alaska are made with one-way parametric
ANOVAs, Kruskal-Wallis nonparametric one-way ANOVAs, and MannWhitney U tests. In these comparisons, as in those described in the
following paragraph, we analyze the data first by the proportion of regular
species in each guild and then by the proportion of individuals that belong
to each guild. We use the terms speciose, diverse, and species rich interchangeably in referring to proportionate or relative guild structure by
species, and the term abundance to mean proportions of individuals.
231
covered nests, including those nesting in tree cavities as well as in other
holes or building dome nests; 3) understory users, including those that
nest or forage principally in the understory «3 m or so); some birds were
assigned to an "understory" guild on the basis of common foraging
and/or nesting locations, but males of these species often sing from the
canopy (e.g., Passerina cyanea, Ixoreus varius, Turdus migratorius, and
Catharus guttatus, to name a few in North America, and Turdus falklandii
in Chile); 4) aerial feeders, including species that often feed on the wing,
either hawking or hover-gleaning insects; 5) canopy seed predators,
including species known to extract seeds from fruits or cones for a major
portion of their diet; 6) leaf-gleaners, including insectivorous species that
feed while moving along or between branches. These categories are a first
approximation, pending an increased information base, especially for
Chile. Many of the guilds used in this chapter are based on the location of
a particular resource, because of our interest in what might happen if the
availability of such resources were altered (Willson, De Santo, Sabag, &
Armesto, 1994). Number 2 above is a clear exception, in that it depends
in part on particular types of constructed nests, rather than a resource.
Nevertheless, we include it, because nesting habits can have a profound
effect on patterns of reproductive success, which in turn can influence
species presence and abundance.
In this preliminary assessment, a given species can belong to more than
one of these guilds, and the sum of all the guilds need not be 100% of the
community. The guild assignment of most midwestern species can be
obtained from Willson (1974), and those for Alaska and adjacent Canada
are from Flack (1976) and Willson (unpublished). For Chiloe, some guild
assignments are shown in Willson, De Santo, Sabag, and Armesto (1994);
in addition, the canopy seed predators are Enicognathus leptorhynchus,
Columba araucana, and Phrygilus patagonicus; aerial feeders include
Elaenia albiceps, Pyrope pyrope, Colorhamphus parvirostris, and
Tachycineta leucopyga (both Elaenia and Pyrope also consume much
fruit); and leaf-gleaners include Anairetes parulus, Colorhamphus parvirostris, Eugralla paradoxa, Scytalopus magellanicus, and Sylviorthorhynchus desmursii.
Statistical Methods
Direct comparisons of diversity, abundance, and guild structure for our
1992 data for Chile and Alaska are made with one-way parametric
ANOVAs, Kruskal-Wallis nonparametric one-way ANOVAs, and MannWhitney U tests. In these comparisons, as in those described in the
following paragraph, we analyze the data first by the proportion of regular
species in each guild and then by the proportion of individuals that belong
to each guild. We use the terms speciose, diverse, and species rich interchangeably in referring to proportionate or relative guild structure by
species, and the term abundance to mean proportions of individuals.