Possible cases of hybridisation between Cracticus torquatus and C. nigrogularis

Cracticus torquatus (Grey Butcherbird) and C. nigrogularis (Pied Butcherbirds), including the juveniles, are generally easy to distinguish between. In the adult stages, Grey Butcherbirds have a white throat, a black cap, white lores (between the eyes and beak), an incomplete white collar, and grey plumage across the back. Pied Butcherbirds have a black throat, dark lores, a complete white collar, and black plumage on their backs. The juveniles are both shades of brown, with light coloured lores already visible in the Grey Butcherbird, while in Pied Butcherbirds, the dark throat/bib is faintly apparent as pale brown with a noticeable sharp transition to the lighter colour of the abdomen. Subsequently, there are very few misidentifications on iNat between the two species.

I've been rummaging through iNat observations for mis-id's and I've found some suspicious looking observations marked as Grey Butcherbirds (linked below), that seemingly possess most features that would identify them as Grey Butcherbirds. However, they also all have patches of black in the throat/bib area, with some having more black than expected on the back (obs - 4), and others with diminished lores (obs - 1, 2, 5). All observations are within the vicinity of Perth. I've looked briefly on Google Scholar and the UNE library for any papers that discuss hybridisation between the species and found none so far. There's no mention of hybrids in any of the field guides I have either.

1 - https://inaturalist.ala.org.au/observations/65467072
2 - https://inaturalist.ala.org.au/observations/41440785
3 - https://inaturalist.ala.org.au/observations/40360665
4 - https://inaturalist.ala.org.au/observations/108492066
5 - https://inaturalist.ala.org.au/observations/67243862
6 - https://inaturalist.ala.org.au/observations/68597079
7 - https://inaturalist.ala.org.au/observations/127816336 (added 25/07/2022, pale back, white lores, patchy throat)

It may be a case that this is variation within the species, differences in ontogeny between eastern and western populations, or I'm just outright mistaken; however, at the moment I'm curious about these observations and I suspect they may be hybrids between Grey and Pied Butcherbirds.

I've tagged a few people below that have identified a lot of Butcherbirds to see what knowledge and thoughts you fine people have.

@thebeachcomber @george_seagull @ratite @twan3253 @deborod @joshuagsmith @jadonald @louisb

References
Cayley, N.W. (1946). What bird is that? A guide to the birds of Australia (11th ed.). Australia: Halstead Press Pty Ltd.
Flegg, J., Madge, S. (1995). Reader digest photographic field guide to the birds of Australia. Australia: Reader's Digest (Australia) Pty Ltd.
Leach, J.A. (1926). An Australian bird book. Melbourne: Whitcombe & Tombs Ltd.
Menkhorst, P., Rogers, D., Clarke, R., Davies, J., Marsack, P., Franklin, K. (2021). The Australian bird guide (Revised ed). Australia: CSIRO Publishing.
Morcombe, M. (2000). Field guide to Australian birds. Australia: Steve Parish Publishing Pty Ltd.
Simpson, K., Day, N., Trusler, P. (1989). Field guide to the birds of Australia. Australia: Penguin Books Australia Ltd.

Publicado por bwjone432155 bwjone432155, 24 de abril de 2022

Comentarios

Super interesting. Agree lots of those look interesting. @nhaass

Publicado por louisb hace 4 meses (Marca)

Pied Butcherbirds are not that common where we are and the areas where the observations are listed above are way out of our area so will leave this to more knowledgeable persons. Good luck, amazing what will hybridise.

Publicado por deborod hace 4 meses (Marca)

To my knowledge this is a known variation of the SW-WA population of Cracticus torquatus leucopterus. I need to check though, if this was discussed in the peer-reviewed literature.

Publicado por nhaass hace 4 meses (Marca)

Nice pick up, I can't recall having noticed this myself. Given all of the obs so far are around Perth, with none anywhere else in Australia thus far despite the many observations of both species and the many areas where the two species are sympatric, this being a geographic variation makes the most sense to me. If otherwise, I'd expect there to be at least a couple of obs elsewhere where the two species overlap

Publicado por thebeachcomber hace 4 meses (Marca)

It would be strange for it to be so localised to Perth if it was a hybrid, as you said, the ranges where they're sympatric is extensive, but it would be interesting if it's a lineage from some one-off event or something. It's probably just a regional variant, which is still fascinating in it's own right.

It is something I'll be keeping an eye out for in Butcherbird observations to see if it occurs beyond the Perth area.

Thankyou all!

Publicado por bwjone432155 hace 4 meses (Marca)

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