Monday, April 9, 2007

Is feeding jelly really okay for birds?

UPDATED June 3, 2023: Rehab clinics are admitting hummingbirds covered in jelly. See my blog post about this here

Back in spring 2004, we had an extreme cold spell in May, right at the peak of warbler, tanager, and oriole migration. Suddenly people were finding dead insectivores on walks through the woods, and my yard was simply hopping with birds, including a wayward Bobolink, 7+ Baltimore Orioles, 5+ Scarlet Tanagers, and 30+ Cape May Warblers all visible at any one time. I went through a huge number of mealworms, and vast quantities of suet, sunflower seed, white millet, and jelly. I've been feeding grape jelly for many years. When my 23-year-old daughter was a preschooler, she'd come home from Montessori school wanting a "pickanic" lunch. I'd fix a sandwich and set her up at the "pickanic" table. On the same table was the orange bowl pictured above (we've had these orange bowls for decades--they came free in dog food), with a plop of grape jelly. And every day while Katie sat there, in flew a catbird to feed at the table right alongside her. When I went out, the catbird wouldn't come anywhere near, but for some reason it approved of my tiny daughter. That orange bowl of jelly was EXTREMELY popular in 2004, when birds were cold and food-stressed!

Anyway, I've long fed jelly to birds. I plop it out in very small amounts usually, because it gets buggy fast and I'm sure bacteria thrives in it, so I don't like having out more than birds can eat in a day. But that spring with all those birds, one morning I filled that bowl half full with jelly because I was going to be gone for several hours and the temperature was in the teens. When I came home, I found a Red-breasted Nuthatch close to death, mired in the jelly so that the only parts sticking out were his beak and eyes. I fished him out and spent hours washing him in warm water, toweling him dry, and allowing him to preen, over and over, until he was releasable. I felt horrible about that, and ever since have been cautioning people about setting out only small amounts of jelly at a time.

But today I got a thoughtful email from Kay Charter, who writes:
I confess that I had a prejudice against this practice [feeding jelly] the first time I saw it...about twenty years ago in a relative's yard. It just didn't look right. So I did some much as it is possible to do, which isn't much and it certainly hasn't been quantified, but it all makes sense. One source was a good friend who is an internist...he said that high sugar foods may trigger a bird's satiety gland, much as it does in children, causing it to feel satisfied when it has had little in the way of nutritional value. He also said that sugar may be addictive for birds as it certainly can be in humans, and that a bird might develop a strong liking for jelly and spend less time searching for natural foods.

Then I queried my friend, Kent Mahaffey, who was manager of the San Diego Wild Animal Park's famous free-flight Bird Show for more than two decades. Kent had primary care responsibility for hundreds of birds from many families. He said he would never allow any birds under his care to have jelly. He added the following:

  • In general, any food that exceeds the balance of sucrose in a bird's natural diet is suspect. Natural nectars contain 12% to 30% sugars, while jams and jellies are more than half sugar. He also said that higher than normal sugar loads may outstrip a bird's ability to adequately process the sugar (as it does in humans); and products high in sugars are an ideal environment for bacterial growth.

He summarized as follows: "Birds developed the way they did by adapting to the environments in which they lived and the foods that sustained them. We do our best for them when we stick as closely as possible to their natural diets."

I know that people have been doing this for decades with no apparent ill effects. But since there is no way to check the effect on internal organs, or, as Kent suggested, bactarial growth, it just seems wise to me to stick with Kent's suggestion...which is to offer foods that are as close as possible to what they evolved with.

SBTH recommends an alternative: grapes. Birds love them, and they have real nutrients, not just sugar.

The bottom line is that while we don't know how this affects our birds, it may (as Kent and my doc friend suggested) be harmful. Why take the chance?


So what's the right answer? I think it's CRITICAL to stop feeding jelly if there is any evidence birds are feeding it to nestlings or bringing fledglings to it--growing babies need protein, not such a heavy carb load. And if an individual birds seems to be spending an inordinate amount of time at the jelly, I'd close down shop, too. At this point, I'm going to probably continue to feed it during migration, especially during cold weather.

Does anyone know of any studies about the relative benefits and harms of feeding jelly to birds? Let me know!