Cuckoo Nestlings - how to pick the difference

Cuckoo Nestlings
How to Pick the Difference

nostril.JPG (9789 bytes)

Cuckoo nestlings are easily distinguished from all passerine host nestlings by their rounded nostrils (left) and zygodactylous feet (2 toes forward, 2 toes back), concave backs and lack of down. More often than not, cuckoo nestlings are found alone in the nest as nearly all Australian cuckoos evict host nestlings and eggs within two or three days of hatching. In this case, the following points are worth noting to aid later identification.

1. the stage of development of the nestling (naked, porcupine, feathered)
2. body mass
3. colour of rictal flanges (at base of bill)
4. general skin colour
5. colour of feathers

Horsfield's Bronze-Cuckoo

2 fairy-wren nestlings,
1 cuckoo (right)

Naked nestling (1-6 d): 1-10 g; no down; rictal flanges white/cream; skin flesh pink on shoulders and belly, grey on head and lower back, the grey spreading and darkening with age.

Porcupine stage (6-11 d): 10-18g; rictal flanges cream/pale yellow; pins on throat uniformly grey with whitish tips.

Fledgling (11-20 d): 18-24 g; rictal flanges pale yellow; feathers of head, back and wings greyish brown with green sheen; light edging to wing coverts and secondaries; feathers on throat immaculate pale grey; may be some barring on flanks; rufous on tail not always apparent while in nest.

12-13 days old

1-2 days old

15-16 days old

6-7 days old

16-17 days old

Shining Bronze-Cuckoo

cuckoo (left),
Western Thornbill (right)

Naked nestling (1-6 d): 1-10 g; rictal flanges bright yellow; skin apricot on shoulders and belly, greenish grey on head and lower back, the grey spreading and darkening to purplish grey with age; some, but not all,nestlings may have short (1 mm) white hairs on the head.

Porcupine stage (6-11 d): 10-18 g; rictal flanges bright yellow; a small patch of yellowish pins among the otherwise grey pins of the throat.

Fledgling (11-20 d): 18-24 g; rictal flanges yellow; feathers of head, back and wings greyish brown with green sheen; ear coverts and upper throat mottled cream and grey with a grey band between throat and breast; some barring on flanks.

6-7 days old

0-1 days old

15-16 days old

3-4 days old

15-16 days old

Black-eared Cuckoo

3-4 days old	Naked nestling (1-6 d): 2-12 g; no down; rictal flanges white/cream; skin coal black, including belly Porcupine stage (6-11 d): 12-22 g; rictal flanges cream/pale yellow; pins dark grey on head, back and wings, cream tipped on chest and flanks Fledgling (11-?20 d); 22-?30 g; rictal flanges pale yellow; feathers of head, back and wings greyish brown with very slight green sheen in sunlight; feathers on belly cream; tail feathers tipped with beige	14-18 days old
8-10 days old		juvenile

Fan-tailed Cuckoo

2-3 days old	Naked nestling (1-6 d): 2.5 -14 g; no down; rictal flanges cream/pale yellow; skin flesh pink on shoulders and belly; grey on head and lower back, the grey spreading and darkening with age; disproportionately large head; oil gland at base of tail conspicuously large, measuring 1 - 2.5 mm. Porcupine stage (6-11 d): 14-24 g; rictal flanges pale yellow; pins on head, back and wings dark grey/black, tipped with yellow on front of wing and on breast and flanks. Fledgling (11-20 d): 24- ?35 g; rictal flanges pale yellow; feathers on head, back and wings mottled light and dark brown; feathers on throat, breast and belly mottled brown, beige and cream; tail tipped with beige.	10-11 days old
6-7 days old		14-15 days old

The photographs on this page may be reproduced on condition that:- (1) you acknowledge the source (Michael Brooker, Belinda Cale) and (2) you do not use the photograph for a commercial purpose.

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