Recently, I spotted a mysterious and baffling bird.*
I regularly take a lunchtime stroll round the lake on the Heslington West campus of the University of York. As will surprise nobody reading this blog, I enjoy the opportunity it presents to watch plenty of wildlife. There’s a pretty standard array of birds, bar the small flock of Snow Geese (Chen caerulescens) that live there.
As you may expect, this is not a truly wild population of this primarily North American bird, instead it’s a pretty content feral group. There’s also several of one of my favourite geese, Barnacle Geese:
Incidentally, if you don’t know the tremendous myth that links Barnacle Geese, Goose Barnacles, and a mad Welsh monk, you should have a read!
So, normally I happily wander round watching the various ducks, geese, coots and moorhens going about their business. But around a week ago something made me stop and stare. An instinct kicked in that something was amiss.
It’s the goose in the foreground we’re looking at. Those behind it are all Greylag Geese (Anser anser). But that looks more like a Canada Goose (Branta canadensis). In fact, had it been amongst the many Canada Geese I’d probably not have noticed. But here it is, tucked up happily with a group of Greylag. Once you’ve started to stare, you start to notice more oddities. Here is a Canada Goose:
Notice the colour of the bill? Black. The legs? Black. Now look again at our intruder:
Pink legs, not black. Orange bill, not black. The black around the neck and head is actually a grey. And that pattern around the cheeks cuts much closer to the eye. So what’s going on? Just a weird variation on a normal Canada Goose? An unusual, exotic species blown in? Or something else altogether? I was pretty certain I knew the answer.
Feral goose populations often hang about together, and as the two most common geese around you often get Canada and Greylag Geese in the same flock. So, when two biologically similar and entirely compatible animals are together, at a certain time of year, there is always a possibility of hybridisation. Given this goose is hanging with the Greylag, and given geese tend to stay with their mothers, we can fairly assume our mystery goose is the result of a male Canada Goose mating with a female Greylag Goose. Anser anser x Branta canadensis
A quick hunt around the web revealed a website, Go Birding, that had a dedicated section on hybrid geese, confirming my suspicion.
So there we go, not a new species. Not a mystery migrant. But a satisfying and interesting little mystery anyway.
To end, a few shots of the lovely lake:
Oh yeah. There’s a daily blog of duck/goose pics from the lakes here: Duck of the Day
* So, yeah, I’ve already blogged about this. But I’m going to just pretend I haven’t!