This year and last: this time last year, from the end of July to the beginning of October, there were hardly any positive cases of bird flu in wild birds recorded by the government surveillance scheme. In 10 full weeks there were only three weeks with positive cases, though these were all Great Skuas, and I guess that we were all labouring under the impression that bird flu was at its summer low point and wondering whether it was going to spring up again in high or low numbers in the coming winter. Indeed, in weeks 20-29 there were no positive records in wild birds detected by this surveillance scheme whatsoever.
What a difference a year makes. We are currently in week 38 of 2022. In weeks 20-29 of 2022 there were nearly 100 positive cases reported involving 20+ species – not a single record in 2021. In weeks 30-37 in 2022, there have already been over 60 positive cases involving over 20 species – compared with those few Great Skuas from last year.
That is a measure of how things have changed. Not a very good measure because this is based on ad hoc tests, in response to the public reporting dead birds and not on any designed sampling regime. The official public figures do not give any indication of how many birds died from bird flu in that a few corpses will be analysed from large die-offs, and it is only the number of corpses giving positive results that are reported, not the number of birds thought to be involved. Negative results are not reported, so there is no prospect of examining the publicly available data and getting any, even the vaguest, impression of how widespread the virus is in the species listed.
The words you have read so far in this blog are, by far, a more detailed comparison of this year’s data with last year’s data than anything made available by APHA, DEFRA etc.
By analogy, imagine that people were falling dead in the streets and some of them were then tested to see whether or not they had died of a particular disease. The records we have for birds are equivalent to those data for people where only some corpses were reported, only some reported corpses were tested, only the positive results were listed in a table each week and if thousands died at a football game it would only be the number of corpses tested that would be reported not the total number of bodies from which that small number was taken.
We should regard the published cases of birds testing positive for bird flu as being in the ‘tip of an iceberg’ category – but even so, this time last year there was very little sign of ice anywhere whereas this year we can clearly see the iceberg and can only speculate about how much more ice there is under the water – but there is a lot, and it’s a lot more than last year.
But what of the species affected?
The species lists for 2021 and 2022:
2021, up to and including week 37, 10 fully identified species: Buzzard, Canada Goose, Great Skua, Knot, Mute Swan, Peregrine, Pheasant, Pink-footed Goose, Red Kite, Rook
2021, an additional 15 species, weeks 38-52: Barnacle Goose, Black-headed Gull, Black Swan, Curlew, Great Crested Grebe, Grey Heron, Greylag Goose, Herring Gull, Kestrel, Lapwing, Mallard, Sparrowhawk, White-tailed Eagle, Whooper Swan, Widgeon (sic).
2022, up to and including week 37, at least 50 fully identified species: Arctic Tern, Barnacle Goose, Blackbird, Black-headed Gull, Buzzard, Canada Goose, Carrion Crow, Common Tern, Coot, Cormorant, Curlew, Eider, Gadwall, Gannet, Golden Eagle, Goshawk, Great Black-backed Gull, Great-crested Grebe, Great Northern Diver, Great Skua, Gey Heron, Greylag Goose, Guillemot, Hen Harrier, Herring Gull, Kestrel, Kittiwake, Little Egret, Little Gull (really?), Mallard, Magpie, Manx Shearwater, Moorhen, Mute Swan, Oystercatcher, Peregrine, Pheasant, Pied Wagtail, Pink-footed Goose, Puffin, Red Kite, Roseate Tern, Sandwich Tern, Sparrowhawk, Tawny Owl, Tufted Duck, White-fronted Goose, White-tailed Eagle, Whooper Swan, Wood Pigeon.
So, twice as many species involved, already, in 2022 as 2021, and five times as many species on a time-for-time comparison.
Some examples; Gannets, raptors and Pheasants:
Gannets: in 2021 I can’t spot any records of Gannets testing positive for bird flu anywhere in the UK (you have a look – I might have missed one because my eyes glaze over a bit looking down the list).
In contrast, the first positive Gannet record in 2022 was in early May (week 19), in Moray. Since then, so far, there have been records of Gannets, positive for bird flu, in weeks, 20, 21, 23, 24, 25, 27, 28, 29, 30, 31, 33, 35, 36 and (last week) 37. Those records often come from within nesting colonies, and the beaches near them, in the early records, but a much more widespread and continuing distribution of records up to the present time. Many people are seeing fresh Gannet corpses on their local beaches in, say, Suffolk, in numbers not seen before, and far away from breeding colonies. And when dying Gannets are being found inland, and in towns too, this is an unprecedented situation. It also suggests that Gannets, and perhaps other species, are travelling quite long distances before succumbing to bird flu, or perhaps are picking it up far from breeding colonies.
The UK has internationally important Gannet populations, on a global scale.
Raptors: in 2021 there were quite a few records of birds of prey which tested positive for bird flu. That doesn’t tell us very much – birds of prey are large and interesting, the wording of which species to report has always mentioned birds of prey, and some of these birds may well be satellite-tagged because of ongoing research projects (and so somebody is keeping an eye on them and their bodies can be found).
The species involved in 2021 were: Buzzard, Red Kite, Peregrine, Kestrel and a single White-tailed Eagle (in Highland). The most commonly reported species was, not surprisingly, Buzzard, in weeks 2, 5, 45, 46, 48, 49, 50, 51 and 52
In 2022 there are far more records and they involve: Buzzard, Red Kite, Peregrine, Kestrel, Hen Harrier (2), Goshawk, Sparrowhawk, White-tailed Eagle (5; in Highland (2), Isle of Wight, New Forest and Argyll and Bute) and Golden Eagle (2; Highland and Western Isles). The most commonly reported species in 2022 is, not surprisingly, still Buzzard, but in weeks 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 32, and (last week) 37 so far.
That two of the White-tailed Eagles are from the area of the southern England reintroduction project is notable.
The Pheasant is an interesting bird. It is a non-native species which is released in very large numbers for recreational shooting each year. When I say ‘very large numbers’ I mean tens of millions, although in recent years, and especially this year, thanks to a combination of Brexit, covid, a Wild Justice legal challenge and bird flu (bird flu has affected imports of Pheasant eggs and chicks from continental Europe) the numbers will be millions, possibly low tens of millions, so many fewer than usual.
In the recently released (last day of August) mitigation strategy from DEFRA and the Welsh government (see here), the authorities decided not to limit, in any way, releases of gamebirds into the countryside despite the increased numbers of cases of bird flu in wild birds.
In 2021, the four positive records of bird flu in free-living Pheasants were simply as follows; week 15 Staffordshire; week 43, Wrexham; week 45, Richmondshire; week 50, South Lakeland.
In 2022, so far (up to and including week 37) there have been three records, all in the past three weeks since DEFRA/Wales issued their strategy: week 35, Cornwall; week 35, Norfolk; week 37, Cheshire East.
There are reports, and I’ve seen discussion about them privately, that the Norfolk cases involved hundreds of Pheasants near the RSPB Strumpshaw nature reserve. There is nothing, you can see, in the official figures that even hints at this.
Let us see how this unfolds over the next few weeks but the blindness of DEFRA to the risk of large scale gamebird releases was pretty obvious but ignored by them.
Note: there may be a few errors (of counting) and omissions in some of these figures. The online versions are not easy to summarise, requiring as it does, eyeballing large tables. Added to which, the nomenclature is inconsistent. Even downloading the .csv files doesn’t fully solve this difficulty – you try it and see! I’m happy for errors to be pointed out – but I don’t think they will be serious ones.
3 Replies to “Bird flu – some comparisons between 2021 and 2022”
Well done Mark for highlighting this again.
There is a serious under-estimate of the species that are suffering from Highly Pathogenic Avian Influenza (HPAI) and the death toll.
An early example of this was at Loch Fleet. Peter Stronach, a consultant ornithologist counted 160 birds of 20 species dead at Loch Fleet reported on 13th May 2022.
Arising from this incident when 160 individuals of 20 species were recorded, only 4 Eiders were tested, of which two tested positive. So only one species (Eider) and two cases go down onto official records. This results in a gross underestimate of the problem. DEFRA did not test other species. Therefor we do know which of these species is vulnerable to HPAI.
I was at Dornoch, Sutherland on 11th September and recorded 11 dead gannets and 7 dead and one dying fulmars along a short stretch of beach. I see fulmar is not even among the list of species that has been recorded with HPAI. I did not report these to DEFRA, perhaps I should have done but I have no confidence in the reporting system.
I also wonder what species of passerine are suffering HPAI as most of these birds are unlikely to be noted by birdwatchers.
NatureScot, which describes itself as Scotland’s nature agency, set up a an Avian Flu Taskforce on 14 July but I’m not sure of its remit and membership.
The comprehensive recording of data is the first step to understanding HPAI but even this seems sadly lacking. This is the most serious disease to hit wild birds in my lifetime and needs more recording, research and funding.
Alister – thanks, and I agree. I am not sure what can be done about the disease, but more information is obviously key. And that is true, I suggest, to combat the impacts on commercial flocks too. I’ve never seen a Mute Swan breaking into a poultry shed so the route to infection, assuming wild birds are involved, must be somewhat more hidden than that.
Mark – one of the things which may be useful is genomic surveillance which may give us more idea of the history, spread and mutation of HPAI. I believe it was widely used for Covid-19. I’m sure there will be other readers of this blog more qualified to know how this could be applied and whether it would be of use.