Botulism at the Ferencmajor fishponds


The affected pond number 3. © György Szimuly

I happily departed for a nice afternoon birding to the Ferencmajor fishponds, my local birding site but the happiness turned into nightmare quite soon. On the long drained pond number 3 I found several dead birds. I first thought the local fishermen shot them to save fishes but then saw a Northern Lapwing and Ruff as well and it became visible that this should be a disaster.

I decided to walk into the pond and check the dead birds. Sadly all the symptoms pointed to the presence of the Clostridium botulinum bacteria which produces neurotoxins among others resulting muscular paralysis. The sings in the mud and the behaviour of a few alive Black-headed Gulls proved my suspicion. The bacteria is spreading when oxygen content of the water is decreasing. The extremely hot weather also doesn’t support the improvement of the situation. In the last two days temperature passed 38℃.


Oversummering Ruffs became victims of the botulism. © György Szimuly

I made an ‘inventory’ of dead birds and also documented it for further actions to avoid mass death of shorebirds. Actually the following birds have been found dead on the single pond:


Very sad series of images of the dead and dying birds. Images was taken by an iPhone 4s. © György Szimuly

Northern Lapwing 1
Ruff 5
Black-headed Gull 28


Dead birds were everywhere on the small mud island. © György Szimuly

So far no other bird species was found but the muddy island seems to be a perfect habitat for many waders including Blac-winged Stilts, Little Ringed Plover, Wood Sandpiper and Ruff to mention a few.

The counted, still alive birds are as follows:

Ferruginous Duck 7
Little Egret 13
Great Egret 6
Black Stork 2
White Stork 3
Eurasian Spoonbill 1
White-tailed Eagle 1
Eurasian Coot 250
Pied Avocet 7
Black-winged Stilt 27
Northern Lapwing 52
Little RInged Plover 21
Whimbrel 1
Spotted Redshank 14
Common Redshank 2
Common Greenshank 1
Wood Sandpiper 54
Green Sandpiper 3
Ruff 47
Yellow-legged Gull 14
Black-headed Gull 110
Common Tern 31
Black Tern 8
Eurasian Hoopoe 3
European Golden Oriole 2

Partially drained ponds are 3 and 10, completely drained is the 9.