Perch hypothermia rides again

You cannot reason a person out of a position he did not reason himself into in the first place.

— attributed to Jonathan Swift, 1667-1745

It was too good to last. After four years of keeping under the radar, Montana wildlife rehabilitator Judy Hoy is once again warning the public about the evils of perches on hummingbird feeders.

Briefly, Hoy believes that hummingbirds that perch to feed on cold sugar water are at risk of hypothermia. From her recent article in the Great Falls Tribune:

If the outside temperature is below 50[° F.] and the sugar water is cold, the birds can become completely hypothermic after drinking two crops full without flying. They then fall to the ground and eventually die from cold and lack of food or are eaten by magpies, cats or other predators.

Hover-feeding isn’t a problem, she says, because the muscle action helps to warm the bird’s body.

She claims that hummingbirds, especially Rufous, are “dying by the thousands every spring” from this phenomenon and is understandably frustrated that hummingbird researchers, feeder manufacturers, and government agencies won’t take her seriously. In this latest article, our self-styled Cassandra gets a little testy:

You may get the impression from this post that I am running out of patience with stupidity and I am!

Same here, Judy.

By her own account, Hoy started her anti-perch campaign in 1985. A quarter of a century is plenty of time to gather an enormous amount of support for her claims, so where is it? Despite repeated requests from skeptics, she hasn’t produced any photos, videos, necropsy results, or other objective evidence to demonstrate that feeder perches cause hypothermia in otherwise normal, healthy hummingbirds. Instead, she continues to rely on anecdotes, opinions, and misinterpretations of cherry-picked scientific research, ignoring more relevant research that refutes her claims.

Over the same 25-year period, people who host wintering hummingbirds have amassed hundreds of thousands of observations of birds perching to feed when the temperatures of both the air and the sugar water are well below freezing (20 degrees or more colder than Hoy’s hypothetical hypothermia threshold), and showing absolutely no ill effects. Additionally, hummingbird banders in the southeastern U.S. have documented hundreds of hummingbirds, including Rufous and Calliope, returning year after year to the same wintering sites. Many of these birds take their first sips of frosty sugar-water every winter morning while resting on feeder perches. Though this doesn’t “disprove” Hoy’s perch hypothermia claims, it does strongly suggest that it’s at worst an extremely rare cause of mortality.

Anna's Hummingbird in my southeastern Arizona yard on a snowy day

None of this seems to make a dent in Hoy’s belief. She responded to these challenges by adding increasingly elaborate and often conflicting justifications for the lack of independent verification: most people never see hypothermic hummingbirds because predators get them first, it happens mostly in “Canada, North Eastern States and…Western Montana,” Rufous are particularly cold-sensitive (!), different species have significantly different “thermodynamics,” pesticides and herbicides sprayed in her area damaged their mitochondria and/or thyroid function.

Unlike Hoy, I don’t expect anyone to take my word on something without evidence. That’s why I wrote a detailed analysis of perch hypothermia way back in 2006, after a message she posted to an online discussion group was forwarded to other groups by well-meaning participants. At Hoy’s request, I sent her all of the evidence refuting her claims, with faint hope that we might lay perch hypothermia to rest once and for all. No such luck. Like True Believers® in so many other crackpot ideas (young-earth creationism, alien abductions, “rods,” homeopathy, etc.), Hoy’s faith is unshakable.

The latest version of her story adds a new and ominous detail, but one that’s easily debunked. In the Great Falls Tribune article, she says:

…Rufous and Calliope are now on Audubon’s red list.

Nope. Both species were listed on the 2002 Audubon Watchlist as yellow (declining), not red (declining rapidly). The 2007 Watchlist includes only the Calliope, still in the yellow category. It’s disappointing, but far from surprising, that even her “new” information is both overstated and outdated.

Removing perches from hummingbird feeders is unlikely to do any significant harm, but it’s equally unlikely to do any significant good. Birds need well-informed friends to help protect them from real and growing environmental threats, so I hate to see the same alarmist claptrap making the rounds over and over and over. Cut the perches off your feeders if you like, but don’t let misinformed prophets of doom distract you from doing things that actually help hummingbirds:

And if you’re still worried about “perch hypothermia,” make your feeder solution richer (3:1 instead of 4:1) during cold weather so that the birds have to take in less cold solution to get the same amount of energy.

About these ads

4 thoughts on “Perch hypothermia rides again

  1. Should feeders in Southern Arizona have extra perches added to prevent HYPERthermia? And maybe umbrellas over the feeders and ice in the sugar water?

    *end sarcasm*

  2. I found one this morning on my window perch thinking it was sitting in rigor mortis! Thought, as per Monty Python, “if it wasn’t nailed to the perch, it would be pushing up the daisies” – I just wish I hadn’t left it there, I thought it might come to. I guess I should’ve looked this up before I left. I would have tried to warm it up. But it wasn’t cold here this morning in Woodbridge, Ontario. It was only a little cool, and I’ve never seen this before.

    • Clearly not a case of PH. If an extremely debilitated hummingbird isn’t in immediate danger from other hummingbirds, larger birds, cats, kids, etc., the safest course of action is to contact a wildlife rehabilitator for advice. You should be able to find one near you using the links in the last paragraph of this post and in my reply to Donna Street’s comment on it.

Add your comment or question

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s