Reasons why we should keep our seed dry

November 16, 2017

By Iriel Edwards, College of Agriculture and Life Sciences, Cornell University, Class of 2020

When it comes to providing for our backyard birds, we want to help them along through rain or shine. Most people want the best for our flying friends, and leaving out a tray or feeder with seed can be a very rewarding method of giving them a boost of resources. But one thing that may cause concern is the potential for our bird feeders to spread disease. New research looked into the potential for bird seed to facilitate the spread of a parasite called Trichomonas gallinae, which can be harmful to birds such as pigeons, doves, and finches. Normally it is transferred from an infected bird through bodily fluids, but could wet seed be a way of transmitting it as well? Researchers wanted to determine if this parasite could persist in bird seed, outside the body of a bird. What they found is good news for all of us feeding birds: the parasite can survive but only in very limited and preventable conditions.

Can the parasites survive outside a host?

A group of Canadian researchers gathered three popular types of birdseed (mixed seed, black-oil sunflower seed, nyjer seed) and created wet and dry versions of each seed type. A low concentration and a high concentration of T.gallinae was added to each type of seed in its dry state and in its wet state. These samples were monitored in very warm conditions (98 degrees F) for more than ten days to see if the parasite could survive outside the body of a bird host.

The researchers found that the parasite was able to persist only in wet seed and only for a couple of days at most. It remained in the wet mixed seed sample the longest (for 48 hours) because the organic matter such as wheat and peas present in most commercial mixed seed was good at retaining water. The best news? No signs of the parasite were recovered from the dry seed samples.

Cleaner, safer feeders

Understanding this parasite’s ability to persist in the food we provide to wild animals is important in preventing avian outbreaks. What we learned from this work is that by keeping seed dry, you can prevent this parasite from persisting. Even if seed is wet, the parasite was only able to persist for a short time at temperatures comparable to the inside of a bird’s body, so it is likely that in cool conditions there is very little risk from T. gallinae. This finding means you need only be concerned if you are feeding birds damp seed in a warm and humid climate. Here are some tips on how to provide a safer feeding source to your backyard friends:

•Keep your feeder out of the “splash zone” of any nearby birdbaths or drinking stations
•Consider bringing your feeder in before a heavy rain if temperatures are very warm.
•Change your seed out regularly if you are in hot and wet weather conditions.
•Choose seed types that contain little to no organic material (buckwheat, peas, and sorghum), e.g. nyjer seed or black-oil sunflower seed.

All in all, you shouldn’t be afraid to offer a batch of seed to a hungry flock of birds. However, it is important that we stay mindful of the roles that we play in other creatures’ lives. Let’s cherish the relationship we have with backyard birds by sharing with them a clean and dry meal!

Research reported in: Persistence of Trichomonas gallinae in Birdseed (2017). Scott McBurney, Whitney K. Kelly-Clark, María J. Forzán, Raphaël Vanderstichel, Kevin Teather, and Spencer J. Greenwood. Avian Diseases Vol. 61, No. 3: 311-315.

<< Return to blog home

11 replies on “Reasons why we should keep our seed dry”

Joann Karges says:

November 17, 2017 at 2:29 pm

I find “digging” out of the feeder the collections of dust or dander from the seed and any fallen seed residue that has gotten wet is a constant and necessary routine in feeder care. This stuff collects not only at the bottom of the feeders but at the feeding holes and can quickly become moldy.

Reply

Pat Moore says:

November 23, 2017 at 9:47 pm

Joann, thank you for that tip!

Reply

Dale Jefferson says:

November 20, 2017 at 9:49 am

You can find additional information about Trichomonosis (including a map of reported incidents in Canada) on the Canadian Wildlife Health Cooperative’s Trichomonosis surveillance page. You can find our fact sheet about the disease, as well as a health note and infographic on how to help reduce the risk of spreading disease among wild birds through your bird feeders and bird baths. http://www.cwhc-rcsf.ca/trichomonosis.php

Reply

Deb Killenbeck says:

November 21, 2017 at 11:06 am

I have only recently started using a nyjer seed “sock.” Rain was predicted and I was wondering about damp seed and mold. So I poured most of it into a more protected feeder. Good to know my cooler north east temperatures will discourage the growth of parasites. But I have decided to only partially fill the sock until we get to the dead of winter where the chances of a soaking rain are gone.

Reply

Lin Faeth says:

November 22, 2017 at 1:01 am

Our birds kick the seed out of a platform feeder and then fly down to feed on the ground! So it’s difficult to keep the seed completely dry although since we live in the hot/dry Central Valley of Calif. nothing stays wet for long after the sprinklers finish and now we’ve got cool days and cold nights.

Reply

Olivia Neuhauser says:

November 23, 2017 at 12:46 pm

I love this! you teach so much about birds and it teaches me so much.

Reply

Olivia Neuhauser says:

November 23, 2017 at 12:48 pm

what a well made guide!
I love it so much!

Reply

gs says:

April 13, 2019 at 12:16 pm

Are there other diseases that can spread from birds to humans from handling and cleaning the feeders?

Reply

Holly Faulkner, Project Assistant says:

April 18, 2019 at 9:01 am

Hello, Yes, there are several diseases that can be passed to humans through contact with feeders; bird droppings, mold, and fungus can all carry diseases (i.e. Salmonella, Histoplasmosis, etc.). However, as long as you take appropriate precautions when cleaning your feeders, they are relatively easy to avoid. Some folks clean their feeders using gloves and a mask – but definitely make sure you wash up good after coming back inside. Read more about how to clean your feeders on our Sick Birds and Bird Diseases page.

Reply

Margo M says:

January 29, 2024 at 10:37 am

I buy “no waste seeds” for my Northern Illinois birds but they spread it all and don’t seem to want to eat it. I would like to know what type of seeds Illinois birds like to eat! Thank you!

Reply

Heidi Faulkner, Project Assistant says:

January 29, 2024 at 7:11 pm

Hello Margo, thank you for reaching out. I wanted to direct you to our Common Feeder Birds Interactive tool here. This can show you what birds are likely to be found in your region, what they like to eat, and even what feeder type they may prefer best. I hope this helps!

Reply