Re: Frogmouths

To: <>, "David James" <>
Subject: Re: Frogmouths
From: "Phil Joy" <>
Date: Mon, 9 Nov 1998 17:36:00 +0800
Hi to all,
             In my National Photographic Index of Australian Wildlife
publication - Cuckoos, Nightbirds and Kingfishers of Australia, G J Ingram
has written on Tawny Frogmouths and under the heading - Breeding, states
that, "Both sexes incubate the eggs, usually the male during the day and the
female at night".  This is corroborated by no less than John Gould whose
observation of Tawny Frogmouths is included in the general text and states
in part that, and I quote, -" In every instance one of the birds was sitting
on the eggs and the other was perched on a neighbouring bough, both
invariably asleep.  That the male participates in the duty of incubation I
ascertained by having shot a bird on the nest, which on dissection proved to
be a male". - end of quote.
As there were no spotlights around in those days it could be assumed that
the bird was shot in the daylight hours so I suppose it would be reasonable
to also assume that the male Tawny does at least some of the daylight
G J Ingram goes on to say that -- "Parent birds share in brooding the eggs
for a month, often in twelve hour shifts, and in feeding the young.

Cheers,    Phil Joy         
P O Box 1510
W A            6725
-----Original Message-----
From: David James <>
To: Chris Dahlberg <>; 
Date: Monday, 9 November 1998 11:49
Subject: Re: Frogmouths

>At 14:27 6/11/98 +1000, Chris Dahlberg wrote:
>>Hello everybody
>>                  I have been watching the posts on Tawny Frogmouths with
>>interest, particularly which sex carries out the incubation and brooding
>>during the day. It has been the experience of John Young that the female
>>carries out these duties and not the male. I am sure that Lloyd Nielsen is
>>of the same opinion but I cannot contact him easily at present.
>Hi Chris and others,
>I am aware that John Young is of the opinion that females carry out the
>incubation and brooding. This is infact the common view. I disagree. I
>looked at several hundred sexed skins of frogmouths in Australian museums
>and searched the literature last year looking for criteria to identify sex,
>age, subspecies, and two forms of individual variation,  morphs and (the
>left over) plain individual variation. This work has been written up,
>edited, refereed and is in press in HANZAB. John is an extremely talented
>observer and I have a lot of respect for him. However, how do you sex birds
>in the field? Behaviour, copulation, morphological criteria established
>from museum studies. Now if birds have sexualy reversed roles in nesting
>behaviour there's a good chance that you could develop the wrong sexing
>criteria. Museum skins are sexed by the morphology of their gonads and so
>independantly of the birds behaviour.
>Having developed reliable criteira for sexing frogmouths (included below) I
>then turned to photos, just to polish descriptions and check points. There
>are plenty of close photos of nesting frogmouths (See especially David
>Holland's "Birds of the Night" and the NPIAW "Cuckoos, Nightbirds and
>Kingfishers of Australia". I was surprised to notice that all the brooding
>and incubating birds of all three species that could be identified to sex
>were male. Gordon Beruldson showed me video footage of a brooding and
>incubating Marbled frogmouth he was observing over an extended period. Day
>and night, who was at the nest, the male. Gordon rarely saw the female. But
>take a look for your self. Most (if not all) photos of Marbled and Papuans
>sitting on nests are grey with marbled bellies and not rufous. Males. Most
>if not all photos of Tawnys on nests are grey morph (all males and most
>females are grey morph), have marbled bellies, big eyebrows behind the eye,
>lack chestnut shoulders and tawny marks around the throat are reduced
>compared with their partner's. Males.
>Schodde & Mason (1982) in their "Nocturnal Birds of Australia" provide some
>confirmation of my findings.
>This work pioneered the sexing of frogmouths, showing that all Papuan and
>marbled frogmouth females are "rufous morph".  Ian Mason's opinions on
>sexing birds are very close to mine and I discussed some problems with him
>regarding Chestnut morph Tawny (only females are chestnut but not all
>female are; the plumage is rare and restriceted to the humid subtropical
>east coast).
>On the subject of nesting duties, S&M where uncertain saying things likeWe
>suspect that both sexes incubate but confirmation is needed; only males
>appear to have been collected off nests by day" (p. 96).
>There is not enough space to reproduce the plumages and related matters
>texts for frogmouths from HANZAB. Last I heard Vol 4 was to hit the news
>stands in Feb. 1999. I can provide some of the relevent snippets from the
>Sexing section. Apologies for the (un)readability of technical style. These
>sections might be hard to follow when divorced from the detailed
>descriptions that identify valid subspecies, describe geographical and
>individul variation etc.
>SEXING    All rufous and chestnut morph birds are female; the one known
>exception is a chestnut morph from Woy Woy, NSW, sexed as a male (AM
>O.39640); sexing unconfirmed; patterning points to male, but ground colour
>otherwise only known in females. Irides said to average paler in males
>(Schodde & Mason); this difficult to asses due to geographical variation,
>but not supported by Table 2. Nevertheless, irides reported as consistently
>yellow in males and more orange in females in s.e. SA. (T. Keens),
>suggesting possible localized differences.
>grey morph:  Differences in plumage between sexes varies geographically,
>and sexing straightforward in some areas, difficult in others. In s.e.
>mainland females usually easily distinguished by two features: (1)
>chestnut-brown, irregular and usually incomplete ring of feathers from chin
>to side of neck and across foreneck that encircles plainer throat; (2)
>strong chestnut ground-colour to lesser wing-coverts, contrasting with
>scapulars ("chestnut shoulders"). Conversely males of s.e. mainland tend to
>have: (1) more recognizable, vaguely square blotches on breast in rough
>checkered or marbled pattern; (2) more distinct scapular braces; and (3)
>more defined broad brown stripe behind eye. These differences not so clear
>but possibly still useful in central, arid and tropical Aust; but
>unreliable or insufficiently known in s.w. WA., Groote Eylandt and Tas.; in
>Tas., males sometimes have "chestnut shoulders". These are average
>differences in plumage so using them is likely to lead to some errors in
>sexing. More information required on interactions between geographical and
>sexual variations.
>SEXING    Generally, males grey or brown and females rufous. However, much
>individual variation and the most grey females are close to the most rufous
>males. Other important differences are: (1) males always have marbled
>pattern on underparts, formed by roughly square, white blotches outlined
>with fine black reticulating lines; females sometimes have a few square
>white blotches (especially on belly), but never extensive and never
>outlined with fine black reticulating lines to produce sharp marbling
>pattern; (2) females consistently have conspicuously plain sandy or
>yellow-brown scapular braces with little overlaid pattern; in males,
>generally white with pattern of fine reticulating black lines or speckling,
>contrasting much less with upperparts; (3) underwing-coverts, distinctly
>barred in males, only faintly patterned in females; (4) bill much more
>massive in males; almost no overlap between sexes in depth and width of
>bill (see Measurements).
>SEXING    Generally, males grey or brown and marbled underneath, and
>females rufous and plainer, but much individual variation. More specific
>differences are: (1) Males tend to be grey to brown on the upperparts with
>comparatively large black-brown and cream spots at tips of feathers,
>whereas females tend to be rufous- or tawny-brown with very fine
>black-brown and cream spots at tips of feathers. (2) Males usually have
>marbled pattern on underparts, formed by roughly square, cream blotches
>outlined with fine black reticulating lines; females either lack marbling
>or have faint version, with buff (124) to pale brown (332D) blotches,
>mostly on belly and thighs and probably never in centre of breast. (3)
>Throat usually marbled on males, uniform on females. (4) Supercilium, broad
>and long on males, narrower and shorter on females. (5) Scapular braces
>usually conspicuous and cream to white in males, subdued and buff to rufous
>in females. For finer differences, see Plumages.
>David James
>PO BOX 5225
>Townsville Mail Centre 4810

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