The diet of the Glossy Swiftlet in the forest habitat was more diverse than that in either the rural or urban habitats (although not significantly so), and contained surprisingly large prey, given the size of the bird itself. The wide diversity suggests that these birds are not particularly selective in their diet. The boluses contained proportionately more coleoptera than those of the Black-nest, White-nest or Mossy-nest Swiftlet (21% vs 5%, 2% and 6% respectively). Whereas the typical flight pattern of the other swiftlet species involves high ranging sweeps (Waugh & Hails 1983), the Glossy Swiftlet forages more often in a position close to (Waugh & Hails 1983) or even under the forest canopy (Medway 1962b), where more
coleoptera may occur compared to higher in the air column. The large size of the prey may be an artefact of the level at which they are feeding (i.e. large prey may be more common at lower altitudes). Glossy Swiftlets are smaller in size than the other species
studied, and this may account for the fewer prey items taken. Glossy Swiftlets feed their nestlings more frequently than do the larger Malaysian swiftlet species
(pers. obs.) and probably fly less far from their colonies to forage.
White- and Mossy-nest Swiftlets are sister species (Chantler & Driessens 1995), being almost impossible to distinguish morphologically. However, even though
their diets are also very similar (Fig. la), there does appear to be some diet separation between the two species: the average size of prey taken by the Whitenest Swiftlet in this study was significantly smaller than that taken by the Mossy-nest Swiftlet.There were significant differences among the diets of Glossy Swiftlets foraging over areas of different landuse.
In general, moving from forest to rural to urban habitat, the proportion of the diet made up of smallerbodied diptera increased while the proportion of hymenoptera decreased. This change in diet may represent a change in food preference, or more probably, simply a change in the available prey related to landuse. Considering the implications of this result for the two commercially important ‘edible nest’ species, changing land-use is likely to have a larger negative impact on the Black-nest Swiftlet, whose diet appears to be very specialized and heavily biased towards hymenoptera, and ants in particular. Since the diet of the White-nest Swiftlet appears to be relatively diverse, already talung a large proportion of diptera, we predict that this species should be able to adapt its diet to the prey available in rural and urban areas, and hence be a suitable candidate for ‘house-nest farming’ enterprises.
The diet of the Glossy Swiftlet in the forest habitat was more diverse than that in either the rural or urban habitats (although not significantly so), and contained surprisingly large prey, given the size of the bird itself. The wide diversity suggests that these birds are not particularly selective in their diet. The boluses contained proportionately more coleoptera than those of the Black-nest, White-nest or Mossy-nest Swiftlet (21% vs 5%, 2% and 6% respectively). Whereas the typical flight pattern of the other swiftlet species involves high ranging sweeps (Waugh & Hails 1983), the Glossy Swiftlet forages more often in a position close to (Waugh & Hails 1983) or even under the forest canopy (Medway 1962b), where morecoleoptera may occur compared to higher in the air column. The large size of the prey may be an artefact of the level at which they are feeding (i.e. large prey may be more common at lower altitudes). Glossy Swiftlets are smaller in size than the other speciesstudied, and this may account for the fewer prey items taken. Glossy Swiftlets feed their nestlings more frequently than do the larger Malaysian swiftlet species(pers. obs.) and probably fly less far from their colonies to forage.White- and Mossy-nest Swiftlets are sister species (Chantler & Driessens 1995), being almost impossible to distinguish morphologically. However, even thoughtheir diets are also very similar (Fig. la), there does appear to be some diet separation between the two species: the average size of prey taken by the Whitenest Swiftlet in this study was significantly smaller than that taken by the Mossy-nest Swiftlet.There were significant differences among the diets of Glossy Swiftlets foraging over areas of different landuse.In general, moving from forest to rural to urban habitat, the proportion of the diet made up of smallerbodied diptera increased while the proportion of hymenoptera decreased. This change in diet may represent a change in food preference, or more probably, simply a change in the available prey related to landuse. Considering the implications of this result for the two commercially important ‘edible nest’ species, changing land-use is likely to have a larger negative impact on the Black-nest Swiftlet, whose diet appears to be very specialized and heavily biased towards hymenoptera, and ants in particular. Since the diet of the White-nest Swiftlet appears to be relatively diverse, already talung a large proportion of diptera, we predict that this species should be able to adapt its diet to the prey available in rural and urban areas, and hence be a suitable candidate for ‘house-nest farming’ enterprises.
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