Kanyana Wildlife Hospital Water Birds with Avian Botulism

As summer progresses, the Kanyana Wildlife hospital sees a rise in the admission of water birds with botulism.

A white-faced heron exhibiting advanced botulism symptoms was admitted to Kanyana’s hospital in the summer.

A white-faced heron exhibiting advanced botulism symptoms was admitted to Kanyana’s hospital in the summer.

Avian botulism is caused by the ingestion of a toxin produced by the bacterium Clostridium botulinum, which grows in low oxygen aquatic environments. During the summer, increased temperatures and decreased water levels provide the optimal conditions for bacterium spores to grow. The botulinum toxin that is produced during the growth of this common, soil- borne bacterium is one of the most poisonous substances known to exist.

The symptoms of avian botulism initially present as a loss of muscle strength, which progresses to complete paralysis. The degree of paralysis depends on the quantity of C. botulinum bacteria and volume of toxin consumed, and the time of exposure. The legs and wings are initially affected, and the bird becomes weak, and reflexes slow; we at the Kanyana hospital refer to this as Stage 1. Symptoms advance until the bird’s legs and wings are immobile, the neck muscles weaken, and the ability to move the eyelids is affected. We describe this as Stage 2 and it is during this phase that these birds are at a high risk of predation if not rescued and admitted into care. They are quite literally, ‘sitting ducks’. Birds in Stage 3 are completely paralysed, and although fully conscious throughout, the inability to move respiratory muscles leads to breathing difficulties and eventual asphyxiation. Unfortunately, we at the Kanyana hospital have found that when a bird reaches this stage of botulinum poisoning, it is beyond recovery.

Upon arrival at Kanyana Wildlife’s hospital, botulism-affected birds are immediately put into intensive care. We place these birds in hotboxes, where we can regulate the temperature. We then proceed with a course of treatment that includes antibiotics and a high volume of fluids to flush out the botulinum toxin. Botulism patients coming into our care are severely calorie-deficient because paralysis has prevented self-feeding. Kanyana’s hospital volunteers hand-feed these birds a high- nutrition diet through tubes until they have sufficiently recovered from their paralysis to feed themselves.

Since the beginning of the year, we have already admitted birds in all three stages of avian botulism, and we have had a lot of success with the Stage 1 and 2 cases received. By providing supportive care, we are often amazed at how quickly these patients can recover. Depending on the severity of their case, we have observed bird patients in our aviaries swimming, flying and behaving as though their botulinum poisoning had never happened – sometimes within a week! Recent Stage 3 patient admissions included a purple swamp-hen, an Australian wood duck (also known as a maned goose) and two pacific black ducks; none of which, unfortunately, we could save.

Recent successes include another wood duck and a pacific black duck, admitted at Stage 1. Both of these ducks were capable of self-feeding from day one, although wobbly on their feet. These patients just needed a few days of care and fluids to flush out the small amount of toxin that they had ingested, and were then ready for release. Another pacific black duck patient, admitted and examined after rescue from a dog attack, was found to be suffering from botulism. The duck’s symptoms, which included an inability to stand, muscle weakness and loss of movement to its eyelids and its neck had made it vulnerable to attack, but after a few days in Kanyana’s care, it had fully recovered.

One of the Kanyana hospital’s more memorable Stage 2 patients was a white- faced heron. Upon admission, the heron could not stand or use its wings, and only had the slightest ability to move its neck. The bird’s eyelids were immobile and dry, and it was extremely underweight from its inability to hunt; this patient was on the verge of Stage 3. We kept the heron in intensive care and administered treatment it until it had recovered enough mobility to place it in an outside aviary. Hospital staff continued observation of the bird’s recovery until it was assessed as being ready to release. After being at death’s door, all this bird needed was fifteen days of care so it could be returned to its territory, fit and healthy.

How can you help native birdlife overcome the threat of avian botulism? Firstly, keep an eye out for birds around waterways that appear to be moving with difficulty, or not at all. As when rescuing any injured animal, capture sick birds carefully, and transport them quickly and safely to a rehabilitation facility for treatment. Secondly, refrain from feeding bread to water birds. Although there has been no direct correlation established between feeding water birds and the incidence of avian botulism, it has been posited that decaying bread increases the nutrient load in water, thereby enhancing the conditions that allow C. botulinum bacteria to flourish. Feeding bread to native water birds results in poor nutrition, the development of unnatural behaviours, and environmental pollution; it’s killing them with kindness. We can all help save our wildlife even with the simplest actions.

Tash Hennings
Hospital Manager

Learn more:

Australian Wildlife Health Network. (2013). Botulism in Australian Wild Birds; Fact Sheet. Retrieved from: https://www.wildlifehealthaustralia.com.au/Portals/0/ Documents/FactSheets/Botulism%206%20Dec%20 2013%20%282.0%29.pdf

Birds in Backyards. (n.d.). To feed or not to feed? Retrieved from: http://www.birdsinbackyards.net/feed-or-not-feed-0

New York State Department of Environmental Conservation. (n.d.). Stop Feeding Waterfowl. Retrieved from: http://www.dec.ny.gov/animals/7001.html

Smith, G. R. (1976). Botulism in waterfowl. Retrieved from: http://wildfowl.wwt.org.uk/index.php/wildfowl/article/ viewFile/523/523