Bird flu through the years

The lists below tell you something of the progression of bird flu in wild birds in the UK since the winter of 2016/17.  The data come from Defra – click here. You are able, and very welcome, to re-do this little analysis and see for yourself.  I expect my version has a few errors in it, because this type of tedious task, extracting data for a purpose that nobody really thought of at the time, is mind-numbingly dull and it’s just the type of thing where I (or anyone else) will make a few errors. They won’t be big errors, and I have checked it, but if you are thinking of using this for any serious purpose (you’re not, are you?) then you should start at the beginning and replicate it yourself. Good luck!

And the data are low quality anyway – see notes at the end.

But, nonetheless this shows which species of wild bird (Defra has a rather odd definition of wild bird – that Red-breasted Goose may not have been wild as some captive birds will be included (although you can’t tell for sure) and places like Slimbridge WWT may have contributed wild ‘wild’ birds and captive ‘wild’ birds (!) to this list) were reported as testing +ve for avian flu in each year since the (not year) of 2016/17.

So, we start in winter 2016/17 when 14 species were reported as testing positive – that’s an ‘annual’ total of 14 species and a running total of 14 species and 14 species that are ‘new’. In 2018, a further 7 species were recorded (in red) bring the running total to 21 species and the total for just 2018 was 15 species. Get it? And so on…


Winter 2016/17:   Black-headed Gull, Canada Goose, Common Buzzard, Cormorant, Greylag Goose, Kestrel, Mallard, Mute Swan, Peregrine, Pochard, Teal, Tufted Duck, White-fronted Goose, Whooper Swan, Wigeon. Total: 14 species, annual 14 species, new 14 species.

2018: Black-headed Gull, Canada Goose, Common Buzzard, Common Gull, Goshawk, Great Black-backed Gull, Great-crested Grebe, Greylag Goose, Herring Gull, Mallard, Moorhen, Mute Swan, Pheasant, Pochard, Tufted Duck. Total 21 species, annual 15 species, new 7 species.

2019: no positive cases reported.

2020: Black Swan, Brent Goose, Common Buzzard, Canada Goose, Great White Egret, Grey Heron, Greylag Goose, Herring Gull, Kestrel, Lesser Black-backed Gull, Little Grebe, Mute Swan, Peregrine, Pink-footed Goose, Shelduck, Sparrowhawk, Whooper Swan. Total 31 species, annual 17 species, new 10 species.

2021: Barnacle Goose, Black-headed Gull, Bewick’s Swan, Black Swan, Canada Goose, Common Buzzard, Curlew, Great-crested Grebe, Great Skua, Grey Heron, Greylag Goose, Herring Gull, Kestrel, Knot, Lapwing, Mallard, Mute Swan, Peregrine, Pheasant, Pink-footed Goose, Red Kite, Rook, Sparrowhawk, White-tailed Eagle, Whooper Swan, Wigeon. Total 35 species, annual 26 species, new 4 species.

2022: Arctic Tern, Barn Owl, Barnacle Goose, Black-headed Gull, Blackbird, Black Swan, Canada Goose, Carrion Crow, Common Buzzard, Common Gull, Common Tern, Coot, Cormorant, Curlew, Eider, Feral Pigeon/Rock Dove, Fulmar, Gadwall,  Gannet, Golden Eagle, Goosander, Goshawk, Great Black-backed Gull, Great-crested Grebe, Great Northern Diver, Great Skua, Great Spotted Woodpecker, Great White Egret,  Grey Heron, Greylag Goose, Hen Harrier, Herring Gull, Kestrel, Kittiwake, Lesser Black-backed Gull, Little Egret, Little Tern, Long-tailed Skua, Magpie, Mallard, Manx Shearwater, Mediterranean Gull, Moorhen, Mute Swan, Osprey, Peregrine, Pheasant, Pied Wagtail, Pink-footed Goose, Pintail, Puffin, Red-breasted Goose, Red-legged Partridge, Red-throated Diver, Red Kite, Roseate Tern, Sandwich Tern, Sparrowhawk, Tawny Owl, Tufted Duck, White-fronted Goose, White-tailed Eagle, Whooper Swan, Wood Pigeon. Total 71 species, annual 64 species, new 36 species.

2023: Arctic Tern, Barn Owl, Barnacle Goose, Black-headed Gull, Canada Goose, Carrion Crow, Common Buzzard, Common Gull, Common Tern, Coot, Cormorant, Curlew, Feral Pigeon/Rock Dove, Fulmar, Gannet, Goshawk, Great Black-backed Gull, Grey Heron, Greylag Goose, Guillemot, Herring Gull, Kestrel, Kittiwake, Lesser Black-backed Gull, Little Tern, Mallard, Mediterranean Gull, Merlin, Moorhen, Mute Swan, Peregrine, Pheasant, Pink-footed Goose, Puffin, Razorbill, Red Grouse, Red Kite, Reed Warbler, Ringed Plover, Roseate Tern, Sandwich Tern, Shag, Sparrowhawk, Tawny Owl, Teal, Whooper Swan, Wood Pigeon.  Total 76 species, annual 47 species, new 5 species.

2024: nothing much to see here yet – click here – but we don’t get so many Whooper Swans in Northants that we can be keen on them snuffing it with bird flu!

So 76 species so far – that’s a lot, particularly as in the last two calendar years there have been annual totals of 64 species (2022) and 47 species (2023). In broad terms there are, let’s say, 300 bird species which occur regularly in the UK every year (some breed, some winter, some just pass through). 76 species is a high proportion of that total. A third of the bird species I’ll see in the UK this year (I don’t get out much) will have tested positive for bird flu in recent years.

In the first few years most cases were in winter and most noticeable in waterfowl – ducks, geese swans etc. Things changed very obviously in 2022, and probably started to change in 2021 actually, when breeding seabirds were very obviously affected. Suddenly it wasn’t a winter thing, it was clearly an all-the-year thing. Last year, 2023 was very much a year of inland Black-headed Gull colonies from the south coast of England northwards being affected with major die-offs even at my local birding patch of Stanwick Lakes in Northants.

The birds apparently affected are very varied. Manx Shearwaters don’t often come across Great White Egrets, and Eiders don’t often breathe on Red Grouse and Great Northern Divers are pretty much unaware of Reed Warblers in their daily lives. This looks like a very inclusive list of UK birds – except for the lack of passerines.

There are very few passerine species on this list. Most species you’ll see on the Big Garden Birdwatch next weekend aren’t here. Does that mean they don’t get bird flu? I doubt it, in fact I’d be surprised if bird flu won’t be slightly affecting BGBW numbers. What it probably means is that few passerines are sent in for analysis. It’s a real faff to collect a bird and send it on and so it tends to be done by professionals such as nature reserve wardens. And, when did you last see a dead Blue Tit that you could have picked up? And when did you last see a dead Mute Swan? Large conspicuous species are well represented in this list compared with small inconspicuous ones – that’s for sure.

The Defra figures don’t tell us how many individuals of each species were affected, they don’t even tell us how many individuals were tested, and they don’t tell us how many showed no signs of avian flu – so in many ways, they don’t tell us much. They do not tell us whether any Blue Tits were tested, but if they were, we know that none tested positive. It’s something, but not much.

And the call was out particularly for corpses of waterfowl and birds of prey – that might be why there are so many of them in the raw data.

There are fewer and fewer positive tests being reported by Defra but we don’t know how many birds are being tested so we can’t know whether the prevalence of the disease is changing.




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