Birdwatch By Susan Campbell

Swirling Birds

T h e retur n of th e chimney swif t s

By SuSa n Ca m pBel l The approach of fall means many things to many people: cooler days, longer nights, the smell of pumpkin spice — all things that I love. But the much anticipated evening congregations of chimney swifts is also near the top of the list. Swirls of these long-distance migrants form at dusk for several weeks as the birds pass through North Carolina on their way south.

If dur ing the war m weather you have seen sma ll, t w it ter ing, fast-fly ing birds wheeling about high overhead, you are likely seeing chimney sw if ts. T hese “fly ing cigars” can be obser ved across the state, but g iven their af finit y for human habitation, they are more abundant where people, buildings and, as their name implies, chimneys are found.

Chimney sw if ts are k now n to breed throughout Nor th Carolina f rom the mountains to the coast. Histor ica lly, they were undoubtedly sparsely distr ibuted, nesting in big hollow trees in old g row th forests in the easter n t wo -thirds of the United States. But as set tlers spread across our state and prov ided abundant nesting cav ities in the for m of chimneys, sw if ts became more common. Today they are v ir t ua lly dependent on humans for their reproductive success. But, unfor t unately, most moder n chimneys w ith caps or extensive lining are unsuitable for the birds. If they can enter a newer chimney, the smooth substrate w ithin the br ick or stone prevents the birds f rom cling ing and, f ur ther more, does not a llow adhesion of the nest (built w ith sma ll stick s and sa liva) to the wa ll. A s a result, recent declines in the chimney sw if t population have been documented across the species range.

Without a doubt, these sma ll birds are incredible fliers, more so than swa llows and mar tins. T hey spend the vast major it y of their wak ing hours on the w ing, except while nesting. Even cour tship and copulation occur in mid-air. Only at night do they descend to rest in a protected spot — which is a lmost a lways a chimney of some sor t.

By late Ju ly, flo ck s of sw if t s b eg in c ong regat ing, fe e d ing on abunda nt aer ia l inse c t s, a nd ro ost ing toget her in larger ch imneys. T hese ag g regat ions b eg in to move sout hward in Aug ust on preva i ling nor t herly a ir c ur rent s to w inter ing g rounds in t he t ropic s. You may fi nd hundre ds sw irl ing around in t he v icin it y of older scho ols, churches a nd of fic e bu i ld ings t hat st i l l ret a in subst a nt ia l br ick ch imneys. Such ch imneys are more spac ious a nd ye ar a f ter ye ar prov ide cr it ic a l st ag ing g rounds for gener at ions of sw if t s. It is a n awesome sig ht to se e t housa nds of ind iv idua ls p our ing into a ro ost site at dark .

Unfor t unately, these unique birds have been misunderstood at this time of year and are of ten thought to be disease- car r y ing bats. A s a result, sig nificant numbers of sites have been capped for fear of being a human hea lth ha zard. Big old chimneys are lost across our state each year to such misunderstandings.

Additiona lly, changes in modes of heating result in large chimneys being retired: usua lly covered and rendered unavailable to sw if ts. Quite simply, there is a genera l lack of awareness of the str uct ures as an impor tant biolog ica l resource. Fur ther more, across most of our state, we are still in the process of identif y ing major roost sites.

Dur ing the w inter months, chimney sw if ts are found in loose agg regations throughout the upper A ma zon basin of South A mer ica. T here they loaf and feed on an abundance of fly ing insects until leng thening days urge them nor thward again. T he ret ur n tr ip br ings indiv idua ls, sw irling and dar ting, back to their summer homes by early Apr il. PS Susan Campbell would love to hear from you. Feel free to send questions or wildlife observations to susan@ncaves.com.