Cetti’s War­bler

A strong pair of lungs are needed for the pow­er­ful song this species uses to fend off ri­vals and also at­tract fe­male part­ners

Bird Watching (UK) - - Contents -

Its pow­er­ful song be­lies its small ap­pear­ance, and this is one bird that’s on the rise

IALWAYS KNEW THAT Cetti’s War­blers had loud songs, but gen­uinely didn’t re­alise quite how loud un­til May this year. I was at Cetti Cen­tral, also known as Radipole Lake, in Dorset, and was in­no­cently walk­ing down one of the paths en­closed on ei­ther side by scrub-fringed reedbeds, try­ing to lis­ten for Bearded Tits. It was here that I was sub­jected to a ver­bal as­sault. Un­know­ingly, I had stum­bled close to a singing post of a Cetti’s War­bler that was right next to the path, so, when it sang, it was no more than a me­tre away.

Hon­estly, that first note made me re­coil. It was like a fire alarm go­ing off. The ve­he­mence of the ex­plo­sion of song al­most swept me off my feet. This piece of reed rage was ex­tra­or­di­nary. Iron­i­cally, I had just been in­volved in a de­light­fully in­tel­lec­tual con­ver­sa­tion about what piece of mu­sic re­sem­bles the Cetti’s War­bler’s brief, dis­tinc­tive out­burst. The rhythm of some singers is quite sim­i­lar to the fa­mous open­ing gam­bit of the first move­ment of Mozart’s Eine Kleine Nacht­musik, al­though the bird is much more force­ful than the el­e­gant piece. Al­ter­na­tively, the fan­tas­tic flour­ish that opens Grieg’s pi­ano con­certo at least re­calls the un­ex­pected power of the bird’s phrase. The Cetti’s War­bler’s in­ter­ven­tion felt like a jolt of heavy metal to ex­plode the cul­tural hot air. That’s one thing we all know about Cetti’s War­blers; they have loud songs, with a par­tic­u­larly strong open­ing and then a few notes fol­lowed by quite a dra­matic fade – a vo­cal short-lived fire­work. These songs, more­over, are given lustily all year round apart from a break in the sum­mer. An­other thing we learn very quickly is that, de­spite their vo­cal pres­ence, these birds are in­cred­i­bly skulk­ing. They spend most of their time out of sight, and can be ex­tremely dif­fi­cult to see. This is at odds to their dom­i­nance of the air­waves, in a sim­i­lar vein to the Nightin­gale. Not many hu­man loud­mouths re­main in the shad­ows, skulk­ing, so it seems coun­ter­in­tu­itive to us that such an ob­vi­ous pres­ence should re­main out of sight. As it hap­pens, Cetti’s War­blers are re­tir­ing, but they aren’t shy. Their ten­dency to re­main in cover has lit­tle to do with a need to be hid­den, but is in­stead an eco­log­i­cal im­per­a­tive. Peo­ple of­ten

comment, when they do fi­nally set eyes on one, that Cetti’s War­bler re­sem­ble Wrens, with their cocked up tails; and there are marked sim­i­lar­i­ties be­tween the two un­re­lated species. It is even pos­si­ble that they might at times ex­clude each other from feed­ing sites. The Cetti’s War­bler ob­tains most of its food by hop­ping on the ground deep within the veg­e­ta­tion, or by cling­ing to stems just above the water sur­face. Its true habi­tat lies at the base of thick­ets which are close to water. One of the best ways to see one, es­pe­cially in the win­ter, is to keep a close eye on veg­e­ta­tion right at the edge of water, ei­ther a lake or a slow flow­ing river. Wrens feed here, too. The Cetti’s War­bler feeds en­tirely on in­ver­te­brates through­out the year, and is ap­par­ently noted for the wide va­ri­ety it takes, in shape and size. It has a predilec­tion for dam­sel­flies in the sum­mer, but will also take minute food items, in­clud­ing aphids. It will take some aquatic lar­vae, sug­gest­ing that at times it is per­fectly happy to get its large, strong feet wet.

Pow­er­ful voice

Once you re­alise the true habi­tat of the Cetti’s War­bler, the loud­ness of its song be­gins to make sense. Birds which skulk of­ten have pow­er­ful voices, be­cause they need to get their sig­nals heard even from deep within low veg­e­ta­tion – this is ob­vi­ously the case in Wrens, which are so fa­mous for their out­bursts. Al­though such birds must some­times come across each other in the labyrinth, most com­mu­ni­ca­tion to ri­vals or mates is vo­cal. There is an­other po­ten­tial rea­son for the loud song, and it is an in­trigu­ing one. It seems that, on the whole, Cetti’s War­blers hold rel­a­tively large ter­ri­to­ries through­out the year – ev­i­dently a sin­gle ter­ri­tory can ex­tend in lin­ear fash­ion for sev­eral hun­dred me­tres, and it is rou­tine for a bird to cover 100 me­tres on its own. It is hard not to con­clude that hav­ing a good pair of lungs is nec­es­sary for a bird with a big ter­ri­tory to keep ri­vals off its patch. There is an in­ter­est­ing case recorded from the con­ti­nent of two Cetti’s War­blers in­volved in a day-long song duel. In con­trast to the in­tense, close-up song du­els we might wit­ness among Robins, these birds re­mained 300 me­tres apart and just shouted at each other! The singing method of Cetti’s War­blers is very un­usual, as any­body who has en­coun­tered them will know. They are com­pletely dif­fer­ent from most birds, which sing con­tin­u­ously and of­ten con­spic­u­ously from a high perch. Cetti’s, on the other hand, sing one or per­haps two song phrases, well within cover, and then tend to fall silent for quite some time. Af­ter a minute or two (up to 14 min­utes has been recorded) it will then sing again, just as loudly and abruptly, but from a com­pletely dif­fer­ent place. A Cetti’s War­bler will have a

num­ber of favoured song posts in its ter­ri­tory, of which about 10 are favourites, and they are of­ten 100 me­tres or more apart. The bird plies the beat of its ter­ri­tory, singing in­ter­mit­tently, and spar­ingly, as it goes. Pre­sum­ably this is the way a male can cover its area. But why would a bird like a Cetti’s War­bler need a large ter­ri­tory? Well, it could be sim­ply to sat­isfy its feed­ing re­quire­ments, par­tic­u­larly dur­ing the win­ter, when in­ver­te­brates are lit­er­ally thin on the ground. In the breed­ing sea­son, how­ever, there is an­other pos­si­ble rea­son. Cetti’s War­blers are highly prone to polygamy. And if you want to at­tract plenty of tal­ent to your ter­ri­tory, pre­sum­ably it pays to point out metaphor­i­cally to the land that you own. A large ter­ri­tory could be a male’s selling point. And, at the same time, who’s to say that a large ter­ri­tory doesn’t help to keep the women apart and con­flicts at a min­i­mum? Re­search into Radipole Lake Cetti’s War­blers found that most males are polyg­a­mous. Of 125 ter­ri­to­rial males counted there, 70 were paired to more than one mate, usu­ally just to two, but oc­ca­sion­ally up to four. These fe­males would all be nest­ing at ap­prox­i­mately the same time, and the ter­ri­to­ries of each male were ex­clu­sive. It is thought that at the be­gin­ning of the breed­ing sea­son there are more fe­males in the pop­u­la­tion than males, al­low­ing the pos­si­bil­ity of polygamy. Bizarrely, the males are all much heav­ier than the fe­males, by a fac­tor of a quar­ter. Is this a fur­ther at­trac­tant? No­body knows. What we do know, though, is that ev­ery male Cetti’s War­bler is pre­dis­posed to at­tract­ing more than one fe­male to its ter­ri­tory. And in­trigu­ingly, the birds seem to do this mainly at night. Dur­ing the day, the song is gen­er­ally di­rected to­wards the ri­val males, to keep them in check. But in the hours of dark­ness, the song is di­rected to­wards at­tract­ing un­paired fe­males. That, there­fore, might solve our clas­si­cal mu­sic puz­zle. What is bet­ter for be­guil­ing a lis­tener than a Lit­tle Night Mu­sic?

A Cetti’s War­bler will have a num­ber of favoured song posts in its ter­ri­tory, of which about 10 are favourites, and they are of­ten 100 me­tres or more apart

BIGMOUTH The Cetti’s War­bler is the clas­sic small bird with a big voice

Rad­pole Lake, Dorset

YOU’D BE LUCKY! Cetti’s War­blers rarely show them­selves this well in ‘real life’ When seen well, the Cetti’s War­bler is a hand­some, though sim­ply pat­terned bird SUB­TLE BEAUTY

WREN-LIKE

The ob­vi­ous pale su­per­cil­ium and cocked tail give Cetti’s War­blers a cer­tain Wren-like look

Newspapers in English

Newspapers from UK

© PressReader. All rights reserved.