Boom­ing pop­u­la­tions

Al­though cli­mate change will have a dev­as­tat­ing ef­fect on many of our birds, warmer tem­per­a­tures are en­cour­ag­ing other species to stay and breed in the UK’S marshy en­vi­rons

Bird Watching (UK) - - Contents - WORDS: MATT MER­RITT

How warmer tem­per­a­tures are en­cour­ag­ing some birds to stay and breed in the UK

BACK IN THE 1970s, when I first started birdwatching, ID was pretty straight­for­ward if you saw a long-legged, long-necked bird. Bit­terns were ex­tremely rare in the UK (and even now, how of­ten do you see one well?), and Spoon­bills were gone, seem­ingly for­ever, so the Grey Heron had the field (or should that be the marsh?) pretty much to it­self.

How things have changed. In south­ern Eng­land, at least, and in­creas­ingly fur­ther north, bird­watch­ers now stand a chance of see­ing a whole host of herons, egrets and sim­i­lar species, and there might well be more to come.

The pioneers

In fact, though, it’s of­ten cited as a case of re­coloni­sa­tion. Spoon­bills had be­come largely ab­sent from the UK from the 17th Cen­tury on­wards, with only oc­ca­sional sin­gle pairs breed­ing and a hand­ful of pas­sage birds seen each year, largely in the spring. The de­struc­tion of much of their pre­ferred habi­tat, as fens and swamps were drained for agri­cul­ture, was the main cul­prit for their demise, al­though hunt­ing and then egg col­lect­ing took their toll, too. But, in 2010, came the an­nounce­ment that at least four pairs had fledged young at Holkham Na­tional Na­ture Re­serve in Nor­folk – the first breed­ing colony for more than 300 years. Spoon­bills typ­i­cally breed in sin­gle-species colonies or, as at Holkham, in small groups within mixed-species colonies con­tain­ing other wa­ter birds, such as Grey Herons, Lit­tle Egrets and Cor­morants, so ex­pan­sion in num­bers and range can be a slow process. Once it gath­ers mo­men­tum, though, it can re­ally take off, and as more and more Spoon­bills also win­ter in the UK, the po­ten­tial for the Nor­folk colony to sprout out­liers rapidly is great. It needs a mix­ture of fresh­wa­ter lakes, reedbeds, and brack­ish la­goons, so will al­ways be tied to coastal ar­eas, but it could ben­e­fit from plans to cre­ate nat­u­ral sea de­fences in many ar­eas by means of planned flood­ing and man­aged re­align­ment. It was a sim­i­lar story with the Lit­tle Egret. It was once prob­a­bly com­mon and wide­spread in Bri­tain and Ire­land – they were listed among the birds eaten at the corona­tion feast of Henry VI in 1429, and 1,000 were eaten at the en­throne­ment of Ge­orge Neville as Arch­bishop of York in 1465. But habi­tat loss, over-hunt­ing and a cool­ing cli­mate saw them de­cline rapidly, so much so that Thomas Bewick, in the first years of the 19th Cen­tury, de­scribed them as al­most ex­tinct. Things got worse. Egret plumes be­came the must-have fash­ion ac­ces­sory, to the ex­tent that, in 1887, one Lon­don dealer sold two mil­lion egret skins. Most came from the hunt­ing of wild birds, with dis­as­trous ef­fects, and by the 20th Cen­tury, it was a bird of south­ern Europe only. This catas­tro­phe did spark a re­ac­tion, though, and in 1889, the Plumage League was formed, a con­ser­va­tion or­gan­i­sa­tion that would be­come the RSPB we all know to­day. Con­ser­va­tion ac­tion in con­ti­nen­tal Europe helped the Lit­tle Egret pop­u­la­tion to grow rapidly, un­til it be­came com­mon in west­ern and then north­ern France, and breed­ing took place in the Nether­lands at the end of the 1970s. Through­out this time, it was a rare va­grant to Bri­tain, but records be­came more and more reg­u­lar, un­til in 1996, a pair first bred at Brownsea Is­land, Dorset.

From there, its num­bers and range have ex­panded as far north as Scot­land, with breed­ing num­bers now es­ti­mated at 750-plus pairs, and win­ter­ing num­bers push­ing up past 5,000 birds.

The next wave

All fairly straight­for­ward, so far. Spoon­bills and Lit­tle Egrets are both largely white, so can’t be con­fused with Grey Herons, and the for­mer are dis­tinc­tive by virtue of their spat­u­late bills, used to sweep through the wa­ter in search of food, and their habit of fly­ing with their necks out­stretched. In the last few years, though, in­creas­ing num­bers of Great White Egrets have been seen in the UK, closely fol­lowed by Cat­tle Egrets. The for­mer, Grey Heron sized but also all-white, bred for the first time in 2012, at Shap­wick Heath Na­ture Re­serve, Som­er­set. The num­ber of win­ter­ing birds con­tin­ues to in­crease, with south coast sites such as Dun­geness be­ing par­tic­u­larly good spots to find them, so the like­li­hood is that they’ll be­come a reg­u­lar breeder, and that their pop­u­la­tion might ex­pand along the same lines as their smaller rel­a­tive’s. Their even smaller rel­a­tive, the Cat­tle Egret, is a species that has ex­panded its range world­wide by a huge amount in the last cen­tury – it even crossed the At­lantic and is now seen in large num­bers in parts of South Amer­ica, and is one of only two species (the other is the Arc­tic Tern), to have reached all seven con­ti­nents. It’s per­haps sur­pris­ing, then, that it has taken so long to make in­roads into the UK, but the story has been much the same as with Lit­tle and Great White: in­creased num­bers of win­ter­ing birds, with in­va­sions in 2007-8 and last win­ter, and first breed­ing in 2008, again in Som­er­set. Given its global suc­cess, and the fact that the pop­u­la­tion in north­ern France is thriv­ing, ex­pect it to be­come a fa­mil­iar sight in Bri­tain, far from its ori­gins on the African sa­van­nah.

Com­ing soon?

So what’s next? Well, Glossy Ibises might be a good bet. There’s a good pop­u­la­tion in south­ern Spain, and in­creas­ing num­bers of these birds have win­tered in Bri­tain in the last decade. In­evitably, that re­sulted in a breed­ing at­tempt at Frampton Marsh RSPB, Lin­colnshire, in 2014, and al­though it wasn’t suc­cess­ful, it’s un­likely that they’ll stop there. It needs well-veg­e­tated marsh­land, and wet mead­ows, a slightly dif­fer­ent re­quire­ment than some of the other species un­der dis­cus­sion, but all the indi­ca­tions are that at least a small breed­ing pop­u­la­tion will estab­lish it­self. There’s also the beau­ti­ful Pur­ple Heron, a pair of which bred at Dun­geness in 2010, the same year that a pair of Lit­tle Bit­terns bred at Ham Wall in Som­er­set. Both are birds with fairly spe­cialised habi­tat needs (shal­low, marshy lakes with large reedbeds for Pur­ple Herons, and reedbeds gen­er­ally, for Lit­tle Bit­terns), so it’s hard to imag­ine them em­u­lat­ing the suc­cess of the egrets, all of which are much more gen­er­al­ist in terms of diet and habi­tat. But there’s no rea­son why a rel­a­tively small but sta­ble breed­ing pop­u­la­tion shouldn’t be­come es­tab­lished in the next few decades, in south­ern Bri­tain at least. Longer shots are Night Heron (an­other species with a very wide range world­wide), and Squacco Heron. Both ap­pear here as va­grants on a reg­u­lar ba­sis, and Night Heron breeds as close as north­ern France, so a cross-chan­nel hop is cer­tainly not out of the ques­tion. Of course, we’ll let you know when­ever that does hap­pen!

Why?

All of which begs the ques­tion as to why these birds are do­ing so well in the UK, at a time when so many species are un­der pressure. Two main rea­sons present them­selves. One is the warm­ing of the cli­mate. For ex­am­ple, the dis­ap­pear­ance of the Lit­tle Egret af­ter the medieval pe­riod is thought, at least in part, to have been due to the ‘Lit­tle Ice Age’. So as tem­per­a­tures have in­creased, so the birds have found the UK more to their lik­ing. That’s true of pretty well all the species dis­cussed – al­though some are mi­gra­tory and could head south to es­cape the worst of the win­ter weather, they pre­fer to be some­where warm enough that bod­ies of wa­ter don’t freeze and that prey items re­main plen­ti­ful, and wet enough that wet­lands (and sur­round­ing agri­cul­tural fields, etc) don’t get too dry. Se­condly, and per­haps more im­por­tantly, the ex­pan­sion of wet­land habi­tats in the UK has given all these species some­where to breed and feed. Con­ser­va­tion schemes, sup­ported by the Euro­pean Union’s Life-na­ture pro­gramme, have re­stored wet­land habi­tat, and created new ar­eas, of­ten on for­mer in­dus­trial land. The big­gest ben­e­fi­ciary, per­haps, is a bird that so many of us rarely see, even when we know it’s present – the Bit­tern. In 1997, there were just 11 boom­ing males, at seven sites, but by 2014 this had grown to 140 at 61 sites, with Ham Wall in Som­er­set the most suc­cess­ful – it has had as many as 20 birds boom­ing at one time. The restora­tion and cre­ation of reedbeds was ob­vi­ously im­por­tant for them, but it also had the spin-off ef­fect of cre­at­ing good habi­tat for other herons, egrets, and sim­i­lar birds. Large, land­scape-scale schemes such as the Great Fen Pro­ject prom­ise to ex­tend that suc­cess fur­ther, al­though Brexit cre­ates un­cer­tainty about the ex­tent to which some of the projects will be able to con­tinue. Cli­mate change looks likely to see the loss of a num­ber of breed­ing species to the UK – moun­tain-dwellers such as Dot­terel and Ptarmi­gan are among those un­der threat – but the rise and rise of the heron and egret fam­ily, and sim­i­lar birds such as the Spoon­bill, may pro­vide us with some sort of con­so­la­tion. Learn to ID the 12 species on the pages over­leaf, and you stand ev­ery chance of find­ing some­thing un­usual for your #My200birdyear list on your next visit to your lo­cal wet­land. And if you do, re­port it to your county bird recorder or on the BTO’S Bird­track app, and tell us about it by email­ing birdwatching@bauer­me­dia.co.uk – you could help iden­tify im­por­tant breed­ing and win­ter­ing sites that can be man­aged to bring in even more birds.

BREED­ING FIN­ERY The ‘ai­grettes’ of Lit­tle Egrets were once highly prized, help­ing their erad­i­ca­tion from the UK Even tiny Spoon­bills have flat­tened, spat­u­late bills! SPOON-FED BABY

GLOSSY IBIS Per­haps this will be the next heron-like bird to colonise the UK

SPOON­BILL Spoon­bills are un­mis­tak­able white birds with mas­sive, weird bills PUR­PLE HERON Could Pur­ple Herons estab­lish a sig­nif­i­cant breed­ing pop­u­la­tion in south­ern Eng­land?

GREY HERON The orig­i­nal heron of our youth is be­ing joined by a host of al­ter­na­tives

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