Won­der­ful world of Wood­cock

They fly like bats, squeak like pigs, and be­have like noth­ing else alive. But we may be about to lose them for­ever

Bird Watching (UK) - - Contents - WORDS: BEN MAC­DON­ALD

We need to un­der­stand this wood­land wader much bet­ter if we are to give it the chance of long-term sur­vival, says Ben Mac­don­ald

DUSK SET­TLES OVER a for­est clear­ing. A Night­jar churrs. Tawny Owls clam­our from the heart of a plan­ta­tion. Then strange croaks and ‘tiziks’ carry across the sharp out­line of the fad­ing pines. There fol­lows an odd, bat-like ap­pari­tion. The bird flies with a com­i­cal lack of ur­gency. It ap­pears to go round in cir­cles – re­peat­edly trav­el­ling the same pre­scribed high­way in the evening sky. Ob­servers of­ten watch with a sense of be­muse­ment. This is, we might think, a very strange bird. A wood­land wader that flies around like a bat, squeak­ing like a pig. We puz­zle, we shrug, and we move on with our daily lives. But in re­cent decades, breed­ing Wood­cock in Bri­tain have dra­mat­i­cally de­clined in num­bers and range. Now is the time to un­der­stand their world.

Few ac­tions are mys­te­ri­ous to those who per­form them. Take the man who skips cer­tain stones on a pavement. He does so for a rea­son. He may look bizarre to passers-by, but in­tent and pur­pose dic­tates his ac­tions. Rarely, if ever, is hu­man or an­i­mal ac­tion per­formed with­out rea­son. The same is true, of course, for birds. And the same is true for the Wood­cock. This bird may leave us in the dark, but they have a clear strat­egy for sur­vival that leaves lit­tle to chance. Their se­cret life has as much pur­pose and or­der as our own. Wood­cock obey the same fun­da­men­tal eco­log­i­cal rules as any other species. The dif­fi­culty is, these rules are hard for hu­mans to de­ci­pher. In this ar­ti­cle, I will try to lay bare the Wood­cock’s life – to show how it makes sense. Few nat­u­ral­ists have cracked the Wood­cock. John Walpole-bond, Des­mond Nether­so­lethomp­son, Gra­hame de Fourges, Tester and Wat­son, Mor­gan and Shorten, An­drew Hood­less – these are some of the pa­tient elite who have given us much of what we know to­day. For an ex­tra­or­di­nary jour­ney into the Wood­cock’s world, Waders and their Breed­ing Haunts, by Nether­so­lethomp­son, of­fers un­par­al­leled in­sight. In this ar­ti­cle, I have sim­ply re­pro­duced, in brief, the find­ings of oth­ers, for your en­joy­ment. Rod­ing is car­ried out by males. As sexes are al­most iden­ti­cal, this was an un­cer­tain point for decades. It was even­tu­ally proven by Marc­strom (1974). A rather un­usual nat­u­ral­ist, Marc­strom shot 400 vo­cal rod­ing birds as they passed over­head in Swe­den over the course of sev­eral days. All but two were males. Hul­ten (1970) found that 6.5% of birds fly­ing at dusk were fe­male, but that none of these fe­male birds used vo­cal­i­sa­tion. True ‘rod­ing’ – vo­cal­ized flight for the pur­pose of ad­ver­tise­ment – is there­fore a pri­mary means of dis­play by male birds. In late win­ter, early, silent rod­ing can take place. I have ob­served rod­ing in sev­eral coun­ties but only noted vo­cal­i­sa­tion from March. Des Fourges, in Sus­sex, found that vo­cal­ized rod­ing could com­mence in early Fe­bru­ary (Nether­sole-thomp­son, 2010). Rod­ing then con­tin­ues through­out the course of the breed­ing sea­son, gen­er­ally un­til the end of July. Males rode on a tightly de­fined cir­cuit. Tester and Wat­son (1973) ob­served rod­ing for 33 days. They found that each male tended to rode the same cir­cuit, over the same ground. Cir­cuits were of­ten aligned with ‘topo­graph­i­cal fea­tures in the

land­scape’, such as rides. This the­ory was given ex­tra weight by the fact that, when one male was killed, an­other, re­mark­ably, re­placed his ex­act cir­cuit two days later. What to hu­mans re­sem­ble ran­dom flights are, in fact, care­fully marked high­ways in the sky. These aerial cir­cuits are the real es­tate of the Wood­cock. Each male has an aerial home range. Hirons (1980) found that cir­cuits some­times over­lap, with some tol­er­ance be­tween males when this hap­pens. Two birds, seen fly­ing and chas­ing to­gether for pro­tracted pe­ri­ods, can be ex­plained by one of two out­comes. Des Fourges be­lieved that most aerial in­ter­ac­tions are be­tween males, with one chas­ing an­other off his cir­cuit. On many oc­ca­sions, three to four birds were in­volved in these prob­a­ble dis­plays of aerial com­pe­ti­tion. Of­ten, the na­ture of the in­ter­ac­tion gives away the gen­der of the bird. I have ob­served sev­eral ‘bump­ing’ en­coun­ters, as birds meet in the air. Most of­ten, these then re­sume rod­ing, after hav­ing re-de­fined their re­spec­tive home ranges. These aerial contacts are, in my own view, rou­tine ter­ri­to­rial dis­putes be­tween males.

A unique courtship

Some­times, how­ever, aerial in­ter­ac­tions in­volve the pur­suit of a fe­male. Nether­sole-thomp­son de­scribes males “twist­ing after the other bird in typ­i­cal wader sex­ual pur­suit pat­tern… giv­ing high-pitched squeak­ing pip-pip-pips”. He cites Brew­ster (1978), who ob­served a vo­cal bird pur­su­ing an­other. It was joined later by a third, with the two pur­su­ing birds be­ing vo­cal. In the For­est of Bow­land in 2013, I watched a dawn ‘spi­ralling’ flight be­tween two birds. One was vo­cal, the other silent. Rather than both birds re­sum­ing rod­ing, the pair de­scended into a nearby strip of birch wood­land. My per­sonal in­ter­pre­ta­tion of this was a dis­play flight,

pre­ced­ing cop­u­la­tion. If the first pur­pose of rod­ing is for males to ad­ver­tise them­selves and de­fine ter­ri­to­ries, the sec­ond is to pro­mote chances of mat­ing. Most field ob­ser­va­tions con­cur that mat­ing is ini­ti­ated via rod­ing. There are two main the­o­ries as to how this hap­pens. Nether­sole-thomp­son (2010) points out that many early nat­u­ral­ists (Pay 1937, Ha­gen 1950 and Muller-us­ing 1960) be­lieved fe­males called down males as they roded over­head. How­ever, there is lit­tle di­rect ev­i­dence for this. Most in­sights point to an­other ex­pla­na­tion. This is that the male at­tracts the fe­male’s at­ten­tion as he rodes over­head. The fe­male then makes some form of aerial con­tact. At this point, dis­play, chas­ing and, if suc­cess­ful, cop­u­la­tion, com­mence. Nu­mer­ous ob­servers bear wit­ness to this. Nether­sole re­counts how a fe­male, in­cu­bat­ing a clutch of eggs, was passed sev­eral times by a male, over­head. Even­tu­ally she flew to join him. M. Chance found that fe­males joined males in flight, after they had been cir­cled sev­eral times. Nests were later found be­low the con­tact point. Des Fourges ex­pe­ri­enced this same con­tact be­hav­iour four times in as many years. Two col­leagues of mine in Lan­cashire, who found eight Wood­cock nests over seven years, did so by care­fully watch­ing for a silent fe­male to ‘rise’ be­low a rod­ing bird. On most oc­ca­sions, the vo­cal male brought his silent mate down into the wood­land. Rod­ing ceased after this point, and mat­ing was pre­sumed to take place. Pairs were later found be­low the ‘con­tact’ point. In each case, nests were found within 100m, up to two weeks later. Walpole-bond ob­served fe­males dart­ing up be­low rod­ing males, with nests found on the fol­low­ing day. Cou­pled with Nether­sole-thomp­son’s ob­ser­va­tions, this sug­gests that fe­males can con­tinue to in­ter­act with males even when in­cu­bat­ing a com­plete clutch of eggs. A vari­a­tion on this in­ter­ac­tion is one where the male de­scends to the fe­male. Puchal­ski (1938) ob­served a male de­scend to a fe­male in­cu­bat­ing an in­com­plete nest – mat­ing fol­lowed. It should be re­mem­bered, though, that such in­ter­ac­tions are far harder to ob­serve. Un­less an ob­server has a ‘fix’ on a fe­male, it’s im­pos­si­ble to say why a male has dropped into a wood. In my mind, a mat­ing de­scent by the male prob­a­bly hap­pens just as of­ten as an as­cent by the fe­male, but is wit­nessed less of­ten by ob­servers. The only proven mat­ing se­quence in Wood­cock is where con­tact is ini­ti­ated via rod­ing. My own view is that ini­tial pair­ing be­gins in the air. Once a nest is es­tab­lished, and ini­tial mat­ing has taken place, the log­i­cal se­quence is that the male de­scends to mate nightly with his now seden­tary mate, un­til her four-egg clutch is com­plete. All of this ex­plains why rod­ing is highly reg­i­mented and deeply log­i­cal. Males rode to de­fine ter­ri­tory, ad­ver­tise pres­ence, and, pos­si­bly, as­sess com­pe­ti­tion. Their ac­tiv­i­ties ad­ver­tise them to ground-based fe­males and ini­ti­ate con­tact. Like other waders, aerial chases lead to ground-based cop­u­la­tion. But why do Wood­cock con­tinue rod­ing through­out the sum­mer once they have, ap­par­ently, paired up? The first thing to con­sider is whether males are polyg­a­mous. Do males aban­don fe­males once they have laid, and head off to find new part­ners? Do they con­tinue rod­ing so they are avail­able to mate again, fol­low­ing the fail­ure of nests? A few things are clear. Al­most all those who have reg­u­larly found Wood­cock nests have done so by en­ter­ing wood­land where a pair’s de­scent took place. Males and fe­males have then been seen to­gether. Nests

Fe­males left the nest 4-7 times a day, av­er­ag­ing 27-29 min­utes off the nest to feed. Birds never for­aged more than 30m from their nests, gen­er­ally fly­ing from near the nest

have fol­lowed close-by. Waders and their Breed­ing Haunts gives a body of ev­i­dence for this, which I will, for rea­sons of space, omit. Not only is this the best-known method for find­ing Wood­cock nests, but these in­sights re­veal what hap­pens be­tween dis­play and nest­ing. Males, it seems, stay close to fe­males un­til the clutch is com­pleted. This is the only be­hav­iour that makes evo­lu­tion­ary sense, be­cause mat­ing must oc­cur four times – once for each egg. Hirons (1980) proved this bet­ter than most, find­ing that ra­dio-tagged males stopped rod­ing for in­ter­vals of one to 11 days while with fe­males. Most prob­a­bly, males as­so­ci­ate with fe­males be­fore, dur­ing, but not after, lay­ing. Fe­males in­cu­bate alone. Des Fourges (1977) stud­ied nest­ing fe­males in­ten­sively, for pe­ri­ods of 24 hours at a time. Fe­males left the nest four to seven times a day, av­er­ag­ing 27-29 min­utes off the nest to feed. Birds never for­aged more than 30m from their nests, gen­er­ally fly­ing from near the nest, but walk­ing back. Feed­ing took place after sun­rise, and shortly be­fore sunset, never dur­ing the night. These are what some rather dis­parag­ingly re­fer to as ‘anec­do­tal’ ob­ser­va­tions. I call them first­hand in­sights. These ob­ser­va­tions are not only in­valu­able, but of­ten re­veal the only pos­si­ble be­hav­iours that make sense in an evo­lu­tion­ary con­text. It is to­tally log­i­cal that fe­male Wood­cocks wake up and leave their nests to feed at first light, re­plen­ish­ing calo­ries lost dur­ing the night. Al­most ev­ery other species does the same. It is log­i­cal that they in­cu­bate pe­ri­od­i­cally through the day, feed be­fore dusk and then hun­ker down to shel­ter eggs when noc­tur­nal ground preda­tors are most ac­tive. As males play no fur­ther role in rais­ing young, it is widely ac­cepted, though not fully proven, that they mate again. This would ex­plain, among other things, con­tin­u­ous rod­ing. Hirons (1980) found that a ra­dio-tagged fe­male, whose clutch had been pre­dated, re-laid 12 days later. Sev­eral other nat­u­ral­ists have found fe­males ca­pa­ble of lay­ing again. Whether Wood­cock are truly dou­ble-brooded is un­known. My in­stinct is that, like sim­i­lar waders, they are pro­grammed to mate again and lay re­place­ments – quickly and rou­tinely – to mit­i­gate high lev­els of pre­da­tion. Fe­males will re-lay, like any wader, but are not proven to raise two broods. Males, in all prob­a­bil­ity, mate again, but it is un­known whether they do so with the same fe­male. Say, how­ever, you have a wood with a sin­gle male and fe­male – a reg­u­lar oc­cur­rence at iso­lated, smaller woods. Un­less the male takes some counter-evo­lu­tion­ary vow of chastity, it seems prob­a­ble he will fur­ther the fu­ture of his species by mat­ing with the same fe­male later in the sea­son. Soon, teleme­try stud­ies will hope­fully prove this be­yond doubt. Wood­cock have evolved a clever breed­ing strat­egy, based around mit­i­gat­ing pre­da­tion and max­i­miz­ing chances of suc­cess. Males give them­selves max­i­mal ex­po­sure to fe­males through con­tin­ued cir­cuits of their ter­ri­tory. Fe­males have ev­ery chance to in­ter­act with one or more males. Males re­main with fe­males un­til clutches are com­pleted, play­ing no fur­ther role in rais­ing young. At this point, fe­males in­cu­bate alone and, if pre­dated, the cy­cle starts over. Males fur­ther the chances of the species by con­tin­u­ing dis­play through­out the sum­mer. Sub­se­quent mat­ing leads to re­place­ment clutches, mit­i­gat­ing ef­fects of pre­da­tion. Se­crets of a se­cre­tive life This, in brevity, is how breed­ing Wood­cocks seem to op­er­ate. But what is their habi­tat? What do they re­quire to sur­vive? And why are they de­clin­ing so fast across the UK to­day? Wood­cocks, for starters, don’t use wood. They don’t nest or perch in trees. They don’t feed in trees. They don’t feed on the prod­ucts of trees – nuts, mast or fruits. Wood­cocks are en­tirely in­sec­tiv­o­rous, nest on the ground, and fly in the sky. Why, then, do they need wood at all? Let’s start with the premise that Wood­cock and Snipe share fun­da­men­tal sim­i­lar­i­ties. Both are

ground-nest­ing, cam­ou­flage-us­ing waders. Both re­quire soft, damp feed­ing grounds rich in spe­cific in­sects. Both re­quire drier sites to nest, where their broods can find cover. Both are, as with any ground-nest­ing birds, ad­versely af­fected by un­due dis­tur­bance and pre­da­tion. Wood­cock and Snipe both dis­play in the air, pur­sue fe­males in flight, and mate and nest on the ground. For Wood­cock, the sole pur­pose of wood­land, then, is to cre­ate op­ti­mal for­ag­ing and nest­ing con­di­tions for its evo­lu­tion­ary needs. A long-term study of Wood­cock habi­tat and diet by Hood­less (2007), con­firmed that earth­worms are the most im­por­tant di­etary el­e­ment in terms of dry weight and fre­quency. In terms of fre­quency of con­sump­tion, adult diet is dom­i­nated, in or­der, by worms, spi­ders, mil­li­pedes, true beetle lar­vae and rove bee­tles. With chick diet, eas­ily-di­gested earth­worms be­come even more im­por­tant, con­sti­tut­ing 50-80% of dry weight biomass eaten. Other key items in chick diet, es­pe­cially in south­ern Eng­land, are ground bee­tles, rove bee­tles and mil­li­pedes. From the de­cid­u­ous plan­ta­tions of Whitwell Wood, in Der­byshire, to the up­land birches of Millden, in An­gus, Hood­less found that these feed­ing re­quire­ments are con­sis­tent. Over­all, stud­ies show dif­fer­ent data on in­sect fam­i­lies con­sumed. All agree, how­ever, that earth­worms are cru­cial for both adults and chicks. Wood­cock se­lect breed­ing sites where avail­abil­ity of these re­sources is high, but where ad­ja­cent sites ex­ist with am­ple pro­tec­tion from preda­tors. Hirons (1987) found that when feed­ing and rear­ing broods, Wood­cock favour young stands of trees, with high earth­worm den­sity and dense ground vege­ta­tion for cover. When nest­ing, birds pre­fer ar­eas with more open ground. Hood­less (1994) found that in birch plan­ta­tions, half of nests were in bracken and heather out­side of wood­land. In Bor­ders, many birds nest on open moor­land, us­ing woods for feed­ing. One Thet­ford For­est keeper told me that Wood­cock, with their 360 de­grees of vi­sion, like to com­mand a wide view of their sur­round­ings when nest­ing.

A fron­tier ex­is­tence

Wood­cock oc­cupy a wood­land fron­tier – be­tween damp, rich, ex­posed feed­ing soils, with cover – and drier, open nest­ing sites, with leaf lit­ter and other cam­ou­flage-en­hanc­ing qual­i­ties. A range of land­scapes can cre­ate these con­di­tions. The New For­est, the Cale­do­nian For­est, the For­est of Dean. All three of these land­scapes har­bour good pop­u­la­tions of Wood­cock, but are very dif­fer­ent in age, com­po­si­tion, alti­tude and char­ac­ter. To­day, how­ever, many of our wooded land­scapes are los­ing Wood­cock at an alarm­ing rate. The trend be­tween the First and New At­lases shows sig­nif­i­cant range losses across Bri­tain. Re­cent ev­i­dence from the BTO’S 2013 Wood­cock sur­vey sug­gests that Wood­cock oc­cu­pied just a third of non-ran­dom woods sur­veyed, and had de­clined by 8% at over­all study sites since just 2003. Oc­cu­pancy ap­par­ently in­creased by 18% in north­ern Eng­land but de­clined by 21% in south­ern Scot­land. Oc­cu­pancy was low­est in south-west Eng­land and Wales, and high­est in north­ern Eng­land, east­ern Eng­land and north­ern Scot­land. Strongholds now in­clude wooded land­scapes such as Strath­spey, Kielder For­est, Thet­ford For­est, the For­est of Dean and the New For­est, ex­tend­ing east­wards into Sus­sex. So what does this tell us about Wood­cock to­day? Firstly, Wood­cock need lots of wood. Fuller

(1982) found that the species prefers large wooded land­scapes. The Wood­cock’s breed­ing strat­egy evolves around a mul­ti­plic­ity of mat­ing op­por­tu­ni­ties. Males and fe­males must have nu­mer­ous chances to in­ter­act, mate and re-lay in re­sponse to high lev­els of ground pre­da­tion. In the long-term, there­fore, only pop­u­la­tions in large, con­nected woods have a strong chance of sur­vival. Re­tain­ing ex­tent is vi­tal for Wood­cock per­sis­tence. Se­condly, Wood­cock show a very strong pref­er­ence for woods with an open field layer. They need ground-level cover – but not un­der­storey, which sti­fles aerial move­ment and re­stricts open space for feed­ing and nest­ing. Trees may cre­ate good feed­ing con­di­tions, but too many trees shut off sun­light that pro­motes hu­mus-rich soils – the layer where earth­worms thrive. Kirby (2005) found that Bri­tish woods, de­void of reg­u­lar clear­ing, cop­pic­ing and ride-cre­ation, are slowly be­com­ing over­grown. Many young conifer plan­ta­tions, once ideal for Wood­cock, are now no longer suit­able. De­cid­u­ous woods have like­wise dark­ened as cop­pice has ma­tured unchecked. Space – rides, glades, clear­ings – must be recre­ated in our forests. Wood­cocks need these open ar­eas to nest, and to ex­ploit large tracts of sun­lit, ba­sic soils for earth­worm food. It is the well-lit, worm-rich spa­ces be­tween trees – not trees them­selves – that Wood­cocks need. Cer­tain wood­land types have proven suc­cess­ful for Wood­cock across Bri­tain, and across many decades. Damp, young birch-woods are prime. These of­ten con­tain rich, damp soils, dense bracken, open glades and well-lit for­est floors. Younger Hazel cop­pice can repli­cate these char­ac­ter­is­tics; so can young conifer plan­ta­tions, with grass and space be­tween trees. In an­cient, ma­ture wood­lands, Wood­cock favour open Beech and Sy­camore, where plants like Dog’s Mer­cury take the place of birch-wood bracken by pro­vid­ing feed­ing cover. In all cases, mois­ture pro­motes earth­worm den­sity and ac­ces­si­bil­ity. Many of our wood­lands, des­ic­cated by over-plant­ing and over-drain­ing, are drying out. We need to en­sure woods re­main both damp and open, with ground cover for preda­tor con­ceal­ment, but plenty of sun­light to foster worms. We need to act fast to re­tain Wood­cock as a Bri­tish breed­ing bird. Then, this bat-like wan­derer may con­tinue to de­light for cen­turies to come.

71

RARE SIGHT It is rare enough to see a Wood­cock om the ground, but two to­gether is ex­cep­tional NIGHT FLIGHT Two birds fly­ing to­gether could mean male on male ag­gres­sion or a pre­lude to mat­ing of a male and fe­male

CRYP­TIC Wood­cocks blend beau­ti­fully with the leafy wood­land floor WOOD­LAND NEST Wood­cock eggs are laid in a min­i­mal nest on the ground Even the fluffy ba­bies have cryp­tic pat­tern­ing for cam­ou­flage in wood­land MINI-WOOD­COCKS

HEFTY WADER

SUNNY GLADES Wood­cocks need sunny glades for max­i­mum earth­worm pro­duc­tion In flight, Wood­cocks are bulky, long billed waders

WORM-EATER The bulk of all Wood­cocks’ di­ets con­sists of earth­worms

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