Black Brant x Dark-bellied Brent Goose hybrid

Black Brant Branta (bernicla) nigricans x Dark-bellied Brent Goose Branta (bernicla) bernicla hybrid

Vagrant Black Brants from either North America or eastern Siberia regularly appear among wintering flocks of Dark-bellied Brent Geese in eastern and southern Britain, and many of these return for successive winters suggesting that they also spend the breeding season with the Dark-bellied Brents. In view of this it is no surprise that hybrids occur frequently and several are now present in eastern and southern Britain every winter.

Some hybrids are relatively obvious given good views, being clearly intermediate between the two parents. Others can be really tricky, with some birds very closely resembling pure Black Brant and may easily be identified as such especially if conditions and views are not perfect. Variation in both parents makes identification of hybrids even harder and whilst backcrossed birds also occur, picking these out would is an unenviable task unless part of a clear family party. Note that bright sunshine is the worst condition for watching Brent Geese as the plumage tones can be impossible to assess accurately.

Although all of the following three birds were darker than the accompanying Dark-bellied Brent Geese, none seemed quite dark enough to be pure Black Brant. The neck collar was variable between the birds, but mostly smaller than on Black Brant. The first and third birds showed a fairly good neck collar, though perhaps not quite so extensive as on pure Black Brant. The middle one was closer to Dark-bellied Brent Goose but was noticeably darker on the back and belly, more evident in the field.

Black Brant x Dark-bellied Brent Goose hybrids with Dark-bellied Brent Geese, Wells (Norfolk, UK), 22nd November 2006

This bird stood out from the Dark-bellied Brent Geese but none of the Black Brant features were quite strong enough for it to be a pure bird.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese, Wells (Norfolk, UK), 19th February 2007

A couple more birds here that were sometimes reported as pure Black Brants. In dull light like this they should have looked more obvious had they been pure. Note too the greyish black tones on the upperparts lacking any of the dark chocolate tones present on pure Black Brants. The two photos show different birds.

Black Brant x Dark-bellied Brent Goose hybrids with Dark-bellied Brent Geese, Wells (Norfolk, UK), 22nd January 2010

The next birds were also sometimes reported as pure Black Brants, and certainly stood out from the surrounding Dark-bellied Brent Geese. The first four photos show a bird with a neck collar that is clearly broken at the front, wrong for pure Black Brant (although an otherwise perfect-looking bird with a broken neck collar appeared a few years ago and it was considered to have been a pure bird). The bird in the other photos has a better neck collar but is not quite dark enough on the back and belly, as well as having rather heavily marked flanks.

The first four photos show one hybrid and the next four show a different hybrid.

Black Brant x Dark-bellied Brent Goose hybrids with Dark-bellied Brent Geese, Holkham (Norfolk, UK), 13th February 2013

An adult Black Brant in Norfolk in autumn 2004 was observed to be paired with a Dark-bellied Brent Goose and accompanying young birds presumed to be its offspring.

Black Brant x Dark-bellied Brent Goose hybrids with Black Brant and Dark-bellied Brent Geese, Wells (Norfolk, UK), 19th November 2094

A very problematic bird had been at Burnham Overy during the winter of 2013/14 which I saw badly a few times. Each time I thought it looked good for a pure Black Brant but I was never able to see it well enough and in suitable light to convince myself. Having discussed the bird with other observers I believe it was another hybrid, but a very difficult bird that was easily identified as a Black Brant. The following winter this hybrid was present - it looked much more obvious to me, but perhaps it was the same returning bird and I just got better views of it? Even in these photos you can see in some it looks obviously a hybrid while in others (the first at least) it is much more like Black Brant.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese, Burnham Overy (Norfolk, UK), 26th October 2014

This was presumably the same bird.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese, Burnham Overy (Norfolk, UK), 28th October 2014

At the same site later in the winter I located the same or another hybrid. This time I noticed that it was accompanying an adult Dark-bellied Brent Goose and three juvenile birds. They were behaving like a family party so I presume the youngsters were backcrossed hybrids.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese and presumed backcrossed hybrid young, Burnham Overy (Norfolk, UK), 1st January 2015

The next bird was more like Dark-bellied Brent Goose - easy enough to identify in dull conditions but when the sun came out it became very hard to pick out.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese, Burnham Overy (Norfolk, UK), 7th December 2015

Next up are some more photos of the regularly returning bird from Burnham Overy. You can see how it morphs from looking pretty much like a Black Brant to being pretty much like a Dark-bellied Brent Goose just by a change of angle to the sun.

Black Brant x Dark-bellied Brent Goose hybrid with Dark-bellied Brent Geese, Burnham Overy (Norfolk, UK), 9th May 2016