Weaver birds are famed for their elaborate nests—teardrop-shaped structures that dangle from telephone poles and treetops, with long entrance tubes that make it impossible for snakes to slink in and nab a baby bird. And dịch vụ Xét nghiệm bệnh xã hội nha trang to imagine a more complex structure—a weaver’s creation can take hundreds of hours and thousands of grass strands to make. But why would these birds go to all that trouble? Some scientists think that the nests are meant to protect chicks from predators, particularly snakes. Others argue that they help chicks find food by allowing them to “see” their parents searching for insects around the nest. But a new study in PLOS One suggests another possible reason: the nests protect the birds themselves by keeping them warm and dry. 
 
 xét nghiệm giun sán khánh hòa studied a total of 56 weaver bird species and 48 icterid species with complete data on nest design and developmental periods. They then matched the data to phylogenies. This allowed them to compare the resulting patterns across the different species and to account for differences in climatic conditions and selection pressures (such as predation and brood parasitism). The results revealed that the design of weaver bird nests—the location and length of the tunnel entrance—is much more consistent than previously thought. It is likely that these traits are under strong selection pressure to keep the birds warm and dry. 
 
For example, the longer tunnel entrances of sociable weavers—which are more centrally located and have a greater thermal mass than nests without this feature—help to buffer changes in ambient temperature. The results also suggest that the design of icterid nests—which are generally more cylindrical in shape and have narrower entrances than those of weaver birds—are adapted to a climate with a high rainfall intensity. 
 
Finally, the results also showed that a male’s level of experience building a nest affects its overall size and structural integrity. The nests of first-year males, for example, tend to be untidy and loosely woven compared with those of mature males. This suggests that a significant part of the variation in weaver bird nests is driven by learning through experience rather than genetics or environmental conditions. 
 
The authors of this study are not convinced, however, that the nests of individual birds can be identified by their structure or color. Rather, they suggest that there may be subtle identifying textures to the weave of individual nests—a clue that might help scientists distinguish between the different individuals that build them. In addition, they have suggested that measures of gross nest morphology are too coarse to capture slight but consistent variations in the way that individual males construct their nests. 
 
It’s not just the sociable weavers who benefit from their massive African nests—other birds use them as homes too, including the familiar chat, pied barbet, ashy-headed finch, and the southern masked weaver. The fact that these other species are willing to live side by side in these enormous family chambers helps them stay cool and dry on hot Kalahari desert days and provides a safety net from the many dangers that lurk in the region, such as predators and extreme weather events.
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