Pathologist discusses salmonella in wild birds

Pontiac residents love wild birds: this fact is driven home to me whenever this column mentions the topic.

For the past couple of weeks, many of you have telephoned about the common redpolls and American goldfinches that are visibly ill.

Mary called from Bristol to say she had discovered several corpses near her home.

And Patsy Emmerson of Shawville also telephoned me. Someone had brought her a sick redpoll, wondering if she could help it survive. Patsy told me that she had it inside her home, in an ice cream container. She was feeding it bird seed as well as giving it water with an eye dropper. Would it get better, she asked me?

I telephoned the Wild Bird Care Centre at 613-828-2849 on her behalf and spoke with Joanne Siddall. She confirmed that the bird would have salmonella, as I’ve reported here in this column. Readers will recall that Ottawa Valley and international birding expert Tony Beck had e-mailed me about this disease weeks ago, and I wrote about it so you would know what’s going on in our wild bird world.

Ms Siddall confirmed my suspicions: that Patsy would be well advised to leave such birds alone because salmonella is infectious. The disease passes quickly to humans, as well as to other animals such as our pets. Caged birds and cats are at risk. “Tell your readers,” said Ms Siddall, “not to bring infected birds into the house.”

She also told me that if I wanted further information I could contact the Canadian Cooperative Wildlife Health Centre. So I did.

On Monday March 11 I interviewed Dr. Doug Campbell, pathologist at this Centre’s University of Guelph location. It is one of four Wildlife Health centres established at Canada’s four main veterinarian schools (the other sites are University of Saskatoon, University of Montreal’s Ste. Hyacinthe campus, and Atlantic Veterinarian College in Charlottetown, PEI).

The four centres represent a diagnostic and surveillance service for wildlife disease. Staff pathologist Dr. Campbell works at the Guelph centre full-time and is the representative of the Ontario Region. His counterpart in Québec is Dr. André Dallaire.

How does this infection manifest itself, I asked him? “The infection is spread from bird to bird, shed through the feces. The most consistent sight of infection is the upper part of the digestive tract. I’ve seen an inflammation and erosion of the lining of the crop and gizzard. The inflammation leads to the bird’s demise and death. But bacteria pass through the system, and is probably also found in other tissue such as the liver.”

What about feeders, I asked? “The root of transmission is bird to bird through the feces. In the wild, birds pass on the infection via their perches.”

We discussed how bird species such as finches are particularly affected by the disease. Although reader Patsy Emmerson said she thought she had also seen a chickadee suffering from salmonella, this species is not as commonly affected.

Why is that, I asked the doctor? Could it be because the finch family are social birds which would more readily transmit the disease from one to another because they tend to travel in flocks?

“Your suggestion sounds reasonable to me. Flocking facilitates transmission. But I have no reason to think that chickadees would be resistant to salmonella.

“This year there are high numbers of finches which increases the densities and feeding stresses. We’re seeing finches with poor body conditions and there are many young birds this year which are simply more susceptible.

“There are many more redpolls this year: they are well-known to mass and this year there’s a bumper crop. The winter foraging is more competitive this year due to numbers.”

And, along with the increased population, comes disease. Nature’s way to control populations.

As well, the “bumper crop” of finches has meant very active feeding stations.

What do you think about feeding wild birds, I asked Dr. Campbell? “Oh I like to stay away from that one,” he quipped, then continued. “This is beyond a disease issue. There are costs and benefits to feeding wild birds. But feeders do play a role in transmitting disease, just as does this mild winter.”

He agreed that bird feeders absolutely must be cleaned, so as to minimize the spread of this disease. This does not mean that feeding once a year is sufficient. The feeders should be cleaned often, with the 10% solution of bleach and water. Afterwards, the feeders must be rinsed.

“The combination of a buildup of bacteria plus a mild winter results in good transmission of disease,” noted Dr. Campbell.

What should my readers do with sick birds, I asked?

“Leave them alone. Absolutely do not bring them into the house. We all share humane impulses and want to ‘do something’ when we perceive suffering. But by the time we see them sick, salmonella infection is very advanced.

“Do not attempt to recover these birds. Leave them. Do not expose yourself to salmonella.”

How does the disease affect living organisms, I asked?

“It is a gastrointestinal disease inducing fever, diarrhea, cramps. Another species affected are cats. I’ve heard of two cases in cats where veterinarians have had to treat them.”

This is also true of humans. If you find a dead, diseased bird, double bag it and put it in the garbage. Double bagging helps to prevent your pet cat from investigating and eating it. But we know that here in Pontiac our garbage gets tipped into open landfill pits. And if your landfill is anything like the one north of Quyon, there are many feral (wild) cats there. Populations of these cats ebb and flow, but it’s prudent for us to recognize that our garbage feeds these critters.

So. What to do about salmonella and infected birds? What to do about dead birds that we see?

First, leave sick birds alone. Do not intervene with nature’s way. They are too ill to save. Under no circumstances bring them into your home. If you presently do have an ill wild bird in your home and are trying to cure it, please release it immediately. Wash your hands and anything else that has come into contact with the bird — or that you have touched. Do not contaminate your self, your home, your own caged pet bird and pets.

Second, double bag the dead birds and put them in the garbage.

But what about double bagging the corpses and sending them for scientific examination?

This is the topic of next week’s column.


Katharine Fletcher is a freelance writer based north of Quyon, Québec.