Chimney Swifts Chimney swifts are small, slender birds that have become a symbol of summer for many. They usually appear during the warm summer months before making their way to more tropical sites for the winter. They are recognized by their spectacular, chirping flocks moving through the sky in synchrony; chimney swifts can be seen most vividly at colonies of hundreds, or even thousands, of individuals forming tornado-like funnels as they descend into a chimney. Unfortunately, the size of the colonies we see today is misleading. Though the numbers may seem remarkable, chimney swift populations have been declining sharply since the 1970s, due primarily to habitat loss. Unlike most birds, chimney swifts cannot perch or stand upright, so they require long, hollow spaces that provide safe roosting and nesting sites. Historically, chimney swifts preferred hollow trees. However, as humans expanded settlements and replaced forests with towns, the species was forced to adapt by using other structures, such as chimneys. In the US, the large-scale shift to alternate heat sources, chimney capping, and the use of prefabricated chimneys has drastically limited their ability to nest. Newer, prefabricated chimneys are often lined with metal flues, which make it impossible for the birds to grip and nest inside. In addition, logging and deforestation make finding suitable overwintering habitat more challenging than ever. In an effort to sustain the remaining population, conservation groups have designed supplemental housing structures known as "Chimney Towers." These towers are designed specifically to provide roosting sites for chimney swifts, which now rely almost entirely on man-made structures like these to survive. However, because this species is remarkably adaptive, minimal conservation efforts—such as keeping traditional masonry chimneys uncapped during the summer months—can improve their chances of survival. Which of the following conclusions can the reader make from the passage?