Tuesday 18 February 2014

Greater White-fronted Goose x Cackling Goose

Greater White-fronted Goose x Cackling Goose (possibly Taverner's Cackling Goose, race taverneri) hybrid, Aurora (Colorado, USA), 8th December 2014 - copyright Cathy Sheeter
(photo ID: 1833)


This bird was associating with Cackling Geese, probably 10-15% larger than average sized Richardson's Cackling Goose (race hutchinsii) (Cathy thinks about the size of a Greater White-fronted Goose).  It appeared heftier in build with thick neck and blocky head, fairly short bill, facial patch smudgy with cleaner white area at base of bill, dirty orange legs (not bright) and no under tail barring.   Cathy tells us this is a different look from others of this hybrid that she has seen and a heftier bird.  Possibly Taverner's Cacking Goose instead of Richardson's as the parent species.


Greater White-fronted Goose x Cackling Goose (possibly Taverner's Cackling Goose, race taverneri) hybrid (same bird as in photo ID 1833 above; with Cackling Goose), Aurora (Colorado, USA), 8th December 2014 - copyright Cathy Sheeter
(photo IDs: 1831-1832)


The next bird was in the same park as the one above - along with about 3000 geese - but was not associating with the bird above.   It was MUCH smaller than the bird shown above - Cathy reckons about 10-15% smaller than average sized Richardson's Cackling Goose (race hutchinsii)  Cathy notes the skinny neck, rounder headed, short bill, dark brown neck, legs dirty orange legs (a bit brighter than the bird above) and no under tail barring.  Given the size and head/bill shape Cathy also considered Ross's x Cackling, but the orange legs would seem odd for such a hybrid.



Greater White-fronted Goose x Cackling Goose hybrid (with Canada and Cackling Geese - in last photo bird at front is Moffit's moffitti/Giant maxima type, middle birds are Lesser parvipes and farther back are Richardson's hutchinsii), Aurora (Colorado, USA), 8th December 2014 - copyright Cathy Sheeter
(photo IDs: 1834-1836)


I thought the extent of white on the head of the bird above was interesting, but Cathy's next bird has even more.  Turns out that this seems to be quite common in Greater White-fronted Goose x Cackling Goose hybrids - more so than Greater White-fronted Goose x Canada Goose hybrids for some reason.  Joern has also pointed out that this phenonemon can occur in other hybrids such as Lesser White-fronted x Barnacle.  Some discussion took place about whether this bird could involve Ross's Goose but note the bright orange legs.  The undertail-coverts are marked as is often the case with Anser x Branta hybrids.



Greater White-fronted Goose x Cackling Goose hybrid (with Greater White-fronted Geese), Longmont (Colorado, USA), 13th January 2014 - copyright Cathy Sheeter
(photo IDs: 1839-1841)


Cathy captured a fine portrait of the next bird along with some studies of the wing veins and rump/tail pattern.







Greater White-fronted Goose x Cackling Goose hybrid (with Cackling Geese), Aurora (Colorado, USA), 18th January 2014 - copyright Cathy Sheeter
(photo IDs: 1889-1895)


Another one showing barring on the undertail-coverts here.  The head shape helped the identification on this bird.  It was with one Greater White-fronted Goose and about 150 Cackling and Canada Geese.  Cathy tells us it was slightly larger than the Greater White-fronted Goose.




Greater White-fronted Goose x Cackling Goose hybrid (with Cackling Geese), Lakeshore Pond, Aurora (Colorado, USA), 17th January 2012 - copyright Cathy Sheeter
(photo IDs: 1896-1899)


The next bird was with Taverner's Cackling Geese and Steve points out that the bird was stouter and had a larger bill than in Greater White-fronted Goose x minima Cackling Goose hybrids.


Greater White-fronted Goose x Taverner's Cackling Goose (race taverneri) hybrid, near Vancouver (Washington, USA), December 2008 - copyright Steve Mlodinow
(photo IDs: 1487-1488)


Compared to that the next bird accompanying minima Cackling Geese was very small and had a very small, narrow bill:

Greater White-fronted Goose x Ridgway's Cackling Goose (race minima) hybrid, near Vancouver (Washington, USA), February 2007 - copyright Steve Mlodinow
(photo ID: 1489)


The next bird closely resembles Greater White-fronted Goose x Canada Goose hybrids but was just a tad bigger than the Cackling Geese with a rather delicate bill.

Greater White-fronted Goose x Cackling Goose hybrid, Poudre Ponds, Greeley, Weld County (Colorado, USA), 26th January 2014 - copyright Steve Mlodinow
(photo ID: 1505)


In the next photo (a different bird), Steve has helpfully identified the large bird at the rear as moffitti/maxima Canada Goose and the bird in profile on the far right as probably a Lesser Canada Goose (race parvipes), though not a typical individual.

Greater White-fronted Goose x Cackling Goose hybrid, Windsor Reservoir, Weld County (Colorado, USA), 26th January 2014 - copyright Steve Mlodinow
(photo ID: 1506)

Both of these birds (photo IDs 1505-1506), especially the second (1506), show more white on the forehead than we might expect.  Steve has noted that this may be key to the ID, suggesting that it may be more common in Greater White-fronted Goose x Cackling Goose hybrids than in Greater White-fronted Goose x Canada Goose hybrids.


Steve tells us that the next bird, among a flock of Ridgway's Cackling Geese (minima) had was longer-billed than the previous hybrid he'd seen of this type, but the fact that it was barely any bigger than the minima supports the identification.


Greater White-fronted Goose x Ridgway's Cackling Goose hybrid (with Ridgway's Cackling Goose, form minima), Bay Center, Pacific County (Washington, USA), 23rd October 2015 - copyright Steve Mlodinow
(photo IDs: 2297-2298)


Alhough the bill looks relatively thick in the next photo, Steve assures us that it was actually small and thin.  The bird itself was not much bigger than the nearby Cackling Geese.


Greater White-fronted Goose x Cackling Goose hybrid (with Cackling Geese), Windsor Reservoir, Weld County (Colorado, USA), 26th February 2016 - copyright Steve Mlodinow
(photo IDs: 2731-2732)


Again, here is a Greater White-front x Cackling with more white on and around the head than you might expect, unlike an earlier Greater White-front x Canada at the same location.


Greater White-fronted Goose x Cackling Goose hybrid (with Cackling Geese), Windsor Reservoir, Weld County (Colorado, USA), 11th December 2016 - copyright Steve Mlodinow
(photo IDs: 2885-2886)


The next bird was found swimming near a very similarly-marked Greater White-fronted Goose x Canada Goose hybrid, causing some confusion.  Steve tells us that compared to its compatriot this bird was smaller-bodied (about the size of Richardson's Cackling Goose hutchinsii) and stubby-billed.


Greater White-fronted Goose x Cackling Goose hybrid, Weld County (Colorado, USA), 10th January 2017 - copyright Steve Mlodinow
(photo IDs: 2908-2909)



(See also: Greater White-fronted Goose x Canada Goose)



Greater White-fronted Goose Anser albifrons
Cackling Goose Branta hutchinsii
Taverner's Cackling Goose Branta hutchinsii taverneri
Ridgway's Cackling Goose Branta hutchinsii minima

2 comments:

  1. Do you think there's any possibility of any of these (such as the very small ones) involving Lesser White-fronted Goose? Of course would probably have to be derived from escapes (and I don;t know how widely kept LWFG is in North America), but might explain some of the variation?

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  2. I suppose it's a possibility though I should think very unlikely given the small one was, I think, among wild not feral geese and I don't think an escaped LWfG is so likely to turn up and hybridise with wild geese. Also I'm not really getting a LWfG feel from the photos - I suppose there are some elements of size and structure that suggest that a bit, but mabye the bill would be even smaller and I suspect pinker too. I'm not sure that the same race of Cackling Goose is involved every time - if not then that may explain some of the variation.

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