New collaborative research from leading conservation scientists at the RSPB (Royal Society for the Protection of Birds), BTO (British Trust for Ornithology), and ZSL’s Institute of Zoology has found that we must change the way we feed our garden birds, or risk losing some of our most iconic species.
I don’t know about you, but my social media feed this week has been flooded with advice, opinions and questionably sourced gossip. For someone whose algorithm is generally just wildlife updates and craft tutorials, I would have been surprised if it weren’t for the fact that all the tea seems to be about garden bird feeders. If you’re also a nature nerd with internet access, you might know what I’m talking about. So, let’s break it down. What’s all this drama about feeding the birds?
The Science
Well, it all goes back to a review recently published by the RSPB about how our garden bird feeding habits may actually be causing more harm than good. Their report includes new guidelines based on the latest conservation science, with the headline being that we should stop all feeding of seeds and peanuts between May and October. This might sound dramatic, especially when so many of us feed our garden birds regularly, but there is very clear scientific evidence for why we need to make this change.
Meet Trichomonas gallinae! We’ll call them Trich for short. They’re a single-celled protozoan parasite which loves nothing more than a crowded party. For the parasite-uninitiated among us, that means a simple, single-celled life form which relies on another organism for its survival (and if you want to learn more about declining parasite populations, you can read all about it here) Unfortunately, they’re more of the uninvited-guest-that-just-won’t-leave type, and they’ve been wreaking havoc on British garden bird populations…
Trich infections cause lesions or sores in the gullet and back of the throat, which make it impossible for birds to swallow. This illness is often deadly, but it takes several days or weeks to progress. All the while, sick birds still attempt to eat, but the lesions in their throats force them to regurgitate food that they are unable to swallow. At busy sites like bird feeders, where lots of birds are sharing one food source, the regurgitated seeds are scavenged.
The disease can spread like wildfire, especially in the warmer summer months. This effect is made even more serious by the fact that birds sick with Trich tend to have less energy and can’t forage normally, so they spend longer at bird feeders than healthy birds – increasing the likelihood of spreading disease. Flat surfaces, such as bird tables or window feeders, are particularly high-risk, because sick birds can stand on them for extended periods of time, picking up and spitting out seeds.
Impacts of the disease
If you’ve been a bird lover for some time, you will probably have seen first-hand how devastating this disease has been for certain garden bird species. The greenfinch, one of our most iconic garden birds, has been most severely affected. Once among the most common visitors to bird feeders, this species has declined by a shocking 62% since the Trich epidemic began1. And in 2021, Greenfinches were placed on the UK Red List of Birds of Conservation Concern.
Similarly, Chaffinches have experienced declines of 37% in just 10 years,1 these losses showing just how important it is to stop the spread of Trich to save these species.
How can you help?
So many nature lovers across the country love the routine of filling up their feeders, and get a lot of enjoyment from seeing nature up close in their own garden. I know that anyone who feeds their garden birds does this from a place of kindness and a desire to help wildlife. So, we must adapt to the evidence-based guidance on how we can best do this.
Right now, the advice to stop feeding only applies in the May-October season, so you can still fill up your feeders in the winter, since Trich parasites don’t spread as easily in the cold. Seed-eating birds also have fewer alternative food sources during this period, so feeders become more important.
In the summer months, we can still provide sources of food for the birds by growing tasty plants like sunflowers, teasels, and ivy. Increasing your garden biodiversity will benefit birds – not to mention a whole host of bugs and the species which feed on them – without creating disease transmission hotspots. Since Trich is currently mostly affecting seed-eating species, it’s still okay to provide fat balls, mealworms or suet in small amounts.
Trich parasites can survive in water, so bird baths are risky, but if you are able to change the water daily, and disinfect your bath once a week, you can still provide a water source for your garden birds.
Crucially, if you see a sick or dead bird, you should report it to the Garden Wildlife Health database to help conservation scientists understand disease patterns and outbreaks. Symptoms can include birds looking fluffed up, lethargic, having wet, matted feathers around the beak, and shallow, laboured breathing.
Thanks for joining me on this bird-nerd gossip deep-dive. I hope we cleared up some of the questions we all had! For the full breakdown, head to the RSPB.
Article written by Maddie Kirby.
References
Primary source:
Wood, C. L., et al. (2023). Our latest guidance on what and when to feed garden birds: Feed seasonally. Feed safely. Available at: https://www.rspb.org.uk/whats-happening/news/how-to-help-garden-birds.
Other references:
- Hammer, H., et al. (2022). Habitat-use influences severe disease-mediated population declines in two of the most common garden bird species in Great Britain. Scientific Reports, 12: 15055. https://doi.org/10.1038/s41598-022-18880-8.
