Bird size

Learn or brush up on small bird iden­ti­fi­ca­tion while you’re out in the field

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

ANY AT­TEMPT TO mas­ter the iden­ti­fi­ca­tion of birds has to take size into ac­count as a ma­jor fac­tor. At the very least, it can help you to nar­row any un­known species down to a much smaller pool of likely sus­pects. At best, it might help you to con­fi­dently sep­a­rate two oth­er­wise very sim­i­lar­look­ing birds.

Look in any field guide, and you’ll see mea­sure­ments given for each species. One is usu­ally the wing­span, but it’s the other one that has the po­ten­tial to cause con­fu­sion. This is the length of the bird, from the end of its bill to the tip of its tail. Sim­ple enough, but you might al­ready have spot­ted that there are a cou­ple of prob­lems with that. These are, sim­ply, that it tends to ex­ag­ger­ate the size of any bird that has a long bill or tail, and it fails to give you any real idea of the rel­a­tive bulk of the bird you’re look­ing at. So, a Long-tailed Tit, for ex­am­ple, can, in a field guide, be shown as roughly the same length (c.15cm) as a Yellowhammer, but that ut­terly fails to con­vey how tiny the tit’s body ac­tu­ally is com­pared to the much chunkier bunting. The next thing to re­mem­ber is prob­a­bly that most birds, seen in the flesh, are smaller than you imag­ine hav­ing pre­vi­ously only seen pic­tures. There are a num­ber of pos­si­ble rea­sons for this. One, of course, is that you quickly be­come used to see­ing the birds through the rel­a­tively nar­row, cir­cum­scribed view pro­vided by your binoc­u­lars or scope – it’s easy to start to ig­nore the wider

con­text that you’re see­ing them in. An­other is that field guides tend to il­lus­trate each species at roughly the same size, even if some do on oc­ca­sion pro­vide side-by-side com­par­isons in cer­tain cases. The bird’s struc­ture also plays a part. A lot of be­gin­ner birders ex­pect waders to be larger than they ac­tu­ally are, be­cause seen on the page, their long legs give the im­pres­sion of some­thing more heron or egret-like. In re­al­ity, they’re of­ten tiny. Fi­nally, and this is a pet the­ory of mine, we grow up with cer­tain ideas of what a ‘stan­dard’ bird size is. When I was a child, for ex­am­ple, the only gulls that made an im­pres­sion on my con­scious­ness were Her­ring Gulls seen on sum­mer hol­i­days, so once I started bird­watch­ing I tended to think of them as an av­er­agely-sized gull. And of course, they’re not. They’re re­ally pretty big. So what can you do to be able to con­fi­dently use size as a fac­tor in mak­ing iden­ti­fi­ca­tions? Well, try fol­low­ing these seven easy steps, and you’ll be well on the way. 1 Use fa­mil­iar birds as ‘yard­sticks’ Start with a few species that you see reg­u­larly and well. In the av­er­age gar­den, you might choose Blue Tit, Chaffinch, Black­bird and Woodpigeon. Get their sizes clear in your mind, and then com­pare any species you don’t know to one or more of these. A Black­cap, say, would be some­where in-between Blue Tit and Chaffinch, and a Mistle Thrush would be big­ger than a Black­bird but much smaller than a Woodpigeon. 2 Use other birds in view as yard­sticks As your bird­watch­ing de­vel­ops, you’re not al­ways go­ing to be in a sit­u­a­tion where one of your reg­u­lar yard­stick species is vis­i­ble. Let’s say you’re study­ing a flock of win­ter waders on the mud­flats of an es­tu­ary, and won­der­ing what that grey and white bird is. It’s stand­ing, hunched, on the edge of a mixed flock of waders. Sev­eral of these, you can see, have bright red legs, and you can con­fi­dently iden­tify them as Red­shanks. Your mys­tery bird is just a lit­tle larger, but noth­ing like as big as the Curlew that’s also in your scope view (which can be iden­ti­fied by its un­mis­tak­able curved bill). So, us­ing your field guide and a bit of de­duc­tion, you can start to edge to­wards iden­ti­fy­ing this as a Green­shank. 3 Us­ing other ob­jects as yard­sticks If all else fails, and your mys­tery bird res­o­lutely re­fuses to go and stand any­where near any other birds, you might still be able to get some im­pres­sion of size from a nearby ob­ject. It’s rel­a­tively easy with birds on your feed­ers, for ex­am­ple – you can com­pare them to the dis­tance between feeder ports, or against the level of seed. But else­where it can be pos­si­ble, too – ev­ery­thing from fences to flow­er­pots can come in handy for mak­ing an ed­u­cated guess at a bird’s size. 4 Judge size against it­self Some very sim­i­lar, and sim­i­larly sized, species are best told apart by look­ing at the dif­fer­ence in size between cer­tain parts of their anatomy. Wil­low War­blers and Chif­fchaffs are close enough in size that it’s im­pos­si­ble to tell the dif­fer­ence in the field, and their plumages are very sim­i­lar, too. But the pri­mary feath­ers on a Wil­low War­bler (those at the tip of the wing) are longer, roughly equal to the length of the ter­tial feath­ers; on a Chif­fchaff, the pri­maries are no more than two-thirds the length of the ter­tials, of­ten less.

And on the closely-re­lated Wood War­bler, as­sum­ing the lemon-yel­low throat and white un­der­parts don’t give the game away, the pri­maries are longer still, reach­ing way down to­wards the end of its short tail. Or take the Ruff, a wader that, in ju­ve­nile and win­ter plumages, seems to get mis­taken for a lot of other things, or over­looked en­tirely (as well as be­ing highly vari­able in size). At all times, though, care­ful watch­ing will re­veal a pro­por­tion­ately small head and a long neck. 5 Con­sider the bird’s pos­ture Some birds look ev­ery cen­time­tre of their given size, while oth­ers seem to do their best to dis­guise their true di­men­sions. Take the way that egrets and herons ‘hunch’ their shoul­ders when at rest – Great White Egrets can ap­pear Lit­tle, and Lit­tle can ap­pear Cat­tle, if all other di­ag­nos­tic fea­tures are im­pos­si­ble to make out. There’s also con­sid­er­able vari­a­tion of pos­ture within a species. A perched, roost­ing Long-eared Owl can ap­pear rel­a­tively dumpy, and, with its ear tufts down, might not look im­me­di­ately dif­fer­ent to a Short-eared Owl. But when dis­turbed, it adopts a very up­right, sleek, elon­gated pos­ture that’s not re­ally like any­thing else. 6 Con­sider the bird’s lo­ca­tion This might sound like stat­ing the ob­vi­ous, but wa­ter­birds in par­tic­u­lar can be de­cep­tive be­cause for much of the time, at least part of them is con­cealed un­der­wa­ter. A Great Northern Diver is a re­ally big bird, but can ap­pear much smaller be­cause it of­ten rides very low in the wa­ter. Waders, too, can look smaller than they should, be­cause for much of the time the bot­toms of their legs will be ob­scured by wa­ter or mud. And what about those birds that we typ­i­cally see at a dis­tance, or in flight, or both. Be­gin­ners are of­ten sur­prised to find the Sky Lark is big­ger than they’d thought, be­cause they’re used to see­ing it as a tiny speck over­head. 7 Con­sider the con­di­tions Time of year can make a big dif­fer­ence to how big a bird ap­pears. On the one hand, birds ac­tu­ally are big­ger at some times than oth­ers – a Wheatear just ar­rived in the UK on its long mi­gra­tion in early March will be thin­ner than a well-fed in­di­vid­ual to­wards the end of sum­mer, and res­i­dent birds ought, by rights, to be thin­ner and smaller as the win­ter goes on, too, be­cause they’ll have been find­ing less and less food. But win­ter also means that birds take steps to beat the cold. An ob­vi­ous one is fluff­ing their plumage out, mak­ing a small bird ap­pear chunkier than it is.

A perched, roost­ing Long-eared Owl can ap­pear rel­a­tively dumpy, and with its ear tufts down might not look im­me­di­ately dif­fer­ent to a Short-eared Owl. But when dis­turbed, it adopts a very up­right, sleek, elon­gated pos­ture that’s not re­ally like else

ADULT LIFE SIZE LONG-TAILED TIT In real life, the Long-tailed Tit is a tiny ball of fluff with a long tail ADULT LIFE SIZE YELLOWHAMMER This bunting can (tech­ni­cally) be the same length as a Long-tailed Tit, but is ac­tu­ally a much larger bird, with a bulkier body ID SE­CRETS è è

JU­VE­NILE LIFE­SIZE GREEN­SHANK Real life Blue Tits are much smaller than you may imag­ine from field guides ADULT LIFE SIZE BLUE TIT

FLOWERPOT SCALE Ev­ery­day ob­jects make great com­par­a­tive scales (here to help judge the size of a Black­bird)

ADULT LIFE SIZE LONG-EARED OWL In this pose, it can al­most ap­pear as small as the tiny Lit­tle Owl

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