For birders all over the world

Ageing Eurasian Spoonbill (Platalea leucorodia)
by Alexander Hellquist

In Sweden, knowledge of the criteria necessary to age spoonbills is limited. As a result of some recent troublesome birds, I have made a study in order to check the credibility of the known, and a few new, age related characters. The results of my visits to the skin collections at the BMNH, Tring, and UZM, Copenhagen, plus many live birds at Schiermonnikoog, are presented here.

1st calendar year (autumn) - 2nd calendar year (spring)

1st calendar year birds in autumn are easily recognisable by their flesh-coloured bill. They show extensive black markings on the wing tips, with almost completely dark outer webs and dark tips on the inner webs of the 2-5 outermost primaries. The inner primaries may show dark tips as well. The primary shafts are black. The outermost and innermost secondaries usually also show black shafts and sometimes small tips, as well as the outer primary coverts. The leg colour varies from (pinkish) grey to mottled dark grey. In many field guides, juvenile spoonbills are shown with pale flesh-coloured legs, but according to my experience this is rarely the case. During autumn the legs become darker, but remain lighter grey than in older birds. The colour of the iris is dull reddish brown. The first year body plumage completely lacks yellow feathers, and sometimes appears to be a "dirty" greyish colour compared to older birds.

The plumage development shown by 2nd calendar year birds in spring varies greatly. Early hatched individuals generally undergo a more extensive body moult during their first winter and spring and thus acquire a more adult-like plumage earlier. The condition of the bird is also of great importance for how the plumage develops; birds in poor condition may retain a juvenile appearance in spring. Even in good condition however, 2nd calendar year birds in spring never show long plumes like older birds. Some lack plumes completely, and some show a small tuft (similar to that of non-breeding adults). Nor do 2nd calendar year birds ever show a yellow breast band, although they may show yellow markings on the face around the base of the bill, as with older birds. The throat pouch is intensely yellow, but never with bright orange red borders in spring as in many older birds. During the first year the bill turns yellow and gradually darkens from the base. Most 2nd calendar year birds in spring show an extensive pinkish yellow outer part of the bill and a more or less greyish base. On many birds the whole bill is yellowish at least through April-May.

Fig.1. 2nd calendar year (same bird as figure 2) Note dark grey bill base, without black mottling). The pale tip is rather small, but has a slight pinkish hue to the yellow. © Paul Hackett.

During summer and autumn the bill becomes more adult-like, but still with a more extensive pale tip and grey base without the black mottling shown by older birds. The naked skin on the lores is often pale, not black as in older birds. The legs are greyer than in adults. The iris colour is still duller red than in older birds, but you need to see this at close range and preferably in sunlight. In cloudy weather, the colour is very hard to judge correctly. In spring, 2nd calendar year birds still retain juvenile remiges with extensive black markings.

Fig.2. 2nd calendar year (same bird as figure 1). Note extensive dark tips on the primaries (more than usual on the inner ones), on the outermost and the two innermost secondaries, and on the primary coverts. Pale lores and a dull brownish eye are good characters as well. © Paul Hackett.

2nd calendar year (autumn) - 3rd calendar year (spring)

The first generation of wing feathers is moulted during the second autumn (or more correctly from summer-winter - the exact moulting scheme is not known, due to lacking data). The second generation of primaries varies a lot in appearance. The inner primaries (which are moulted first) can be similar to those of the 1st generation, but the innermost 3-5 feathers usually lack black tips, and only show black shafts or no black markings at all. The outer primaries usually lack dark outer webs, and only show black tips which vary in size. The outer primary coverts usually have black shafts and small black tips. Rarely, all 2nd generation wing feathers are completely white. This may apply to as many as 10 % of the birds that have completed their moult (that is, 3rd calendar year birds in spring). In the field, birds with only black shafts or small black tips on the primaries appear completely white-winged.

In general, 3rd calendar year birds in spring closely resemble older birds, and some, which show limited or no black markings on the wings, cannot be positively aged. In spring, most lack yellow breast band, but rarely a faint one is present. While considering this, it's important to remember that older spring birds may lack breast band as well, due to poor condition. 3rd calendar year birds nearly always acquire plumes in spring, usually rather short and white, but sometimes as long and yellow as in older birds. The yellow throat pouch often has orange red borders. The bill pattern is usually identical to that of older birds, but some 3rd calendar year birds may have a slight pinkish hue to the yellow, and/or clearly more extensive yellow. Still, the bill pattern can't be used as anything but an indication of the age. The lores are dark in spring and summer. As in 2nd calendar year, the colour of the legs is more greyish than on older birds, but this is probably difficult to judge on lone birds in the field. On birds feeding in water the legs may appear black, as in adults. The colour of the iris is intensively red.

Fig.3. 3rd calendar year (same bird as fig.4). A rather typical bird, showing an adult-like bill pattern and eye colour as well as dark lores, but grey tibia and black on wing (hard to see in this picture).© Stephen Blain

3rd calendar year (autumn) - 4th calendar year (spring)

During autumn most 3rd calendar year birds acquire completely white primaries. Perhaps 10 % still have small black tips on the outer primaries, and a few more show some black shafts. These black markings are very hard to see in the field.

Fig.4. 3rd calendar year (same bird as fig.3). © Stephen Blain.

In spring, a bird with a yellow breast band, long yellowish plumes, a small yellow bill tip, black legs, red irises, and some black shafts and/or small tips on the primaries is most probably in its 4th calendar year. It cannot be said for sure, though. From Holland, Otto Overdijk reports a few 5th calendar year birds with black markings on the wings, as well as one 6th calendar year bird. In 4+ birds, the look of the breast band and of the plume depends on the condition of the bird. There are no differences in plumage between males and females (the best separating character would be the longer bill in males, obvious on direct comparison). The shape and size of the yellow bill tip vary individually (and can be used as a thumbprint to recognise individual birds).

In spring, I think almost all 2nd calendar year birds are possible to age in the field, and most, perhaps 80-90%, of the 3rd calendar year birds. Outside the breeding season, spoonbills are more difficult to age, but the most reliable characters (the colour of the iris and the legs, in combination with a "correct" wing tip and bill pattern) are useful all the year round.

In Sweden, 67 spoonbills have been found up to the year 2000. 36 have been aged. Of these, only two were 2nd calendar year birds and one was a 3rd calendar year bird. The low share of subadults is perhaps not surprising, when considering that most birds do not return to their breeding grounds until they reach their 4th calendar year. Statistics from Holland show that less than 5 % of the 2nd calendar year birds return, and about 8 % of the 3rd calendar year birds. Still, many 2nd calendar year birds and probably even more so 3rd calendar year birds migrate northwards in spring, even though they are not intending to breed. Because they are difficult to separate from older birds, my guess is that 3rd calendar year birds are overlooked in Sweden.

The most important age characters

	Plume	Breast band	Bill	Leg colour	Iris colour	Wing pattern
1st cy autumn	No	No	Flesh coloured	(Pinkish) grey	Brownish red	Extensive black
2nd cy spring	Sometimes a white tuft	No	Extensive yellow tip, grey base	Grey	(Brownish) red	Extensive black
3rd cy spring	Usually short and white	No (rarely faint)	Generally more yellow than in 4th+ cy	Dark grey	Intensively red	Usually little black
4th cy+ spring	Long yellow	Yes	Varies, but limited yellow tip	Black	Intensively red	No black (4th cy may show some)

Fig.5. 2nd calendar year bird. Compare with the bird in figure 4. Note still greyer legs, duller eye and pale lores. © Stephen Blain.

Acknowledgements

Many thanks to Erik Hirschfeld for information about the Swedish findings, to Bjorn Malmhagen for valuable comments on the script, to Stephen Blain, Nigel Blake, Paul Hackett and Mark Lynes for allowing me to use their photos, to the staff at the BMNH in Tring and UZM in Copenhagen and last but not least to Otto Overdijk for information and help with field studies in Holland.

More Spoonbill images at surfbirds:

1: http://www.surfbirds.com/Rarities/ukstoppress-july0501.html The picture with two birds feeding together shows a 2nd calendar year bird and a 3rd calendar year bird. Note the greyer legs, bill and lores of the younger bird. (The older bird is also shown in URL #2 (below) and in figures 3 and 4 above, and the younger bird is shown in figure 5 above).

2: http://www.surfbirds.com/Rarities/ukstoppress-july-0401.html 3rd calendar year bird (same as in URL #1 and figures 3 and 4). Note dark red iris, black wing tip (most probably more extensive than ever shown by 4th calendar year), and adult-like bill with a watered base and a small yellow tip.

3: http://www.surfbirds.com/Rarities/ukstoppress-july-0301.html 2nd calendar year bird. (same bird as in picture 2 and 3) Adult-like bill (although too grey and not watered), but greyish tibia, extensive dark wingtip, pale lores and a rather dull eye colour (hard to judge though) favours 2nd calendar year.

4: http://www.surfbirds.com/Rarities/ukstoppress0_09.html This is not a 1st summer bird, most probably a 2nd summer. Note dark lores, dark legs, and dark, black base of the bill, which are all characters that don't fit with a 2nd calendar year bird. Although hard to see, the eyes look dark red, not brownish. Rather extensive black on the outer web of the outermost primary (seen on the lower right picture) suggests a 3rd calendar year bird.