This article was in a Costa Rica online paper today.



Pollinating Birds Won't Cross Cleared Land

Scientists from Oregon State University have glued tiny transmitters to hummingbirds in Costa Rica to figure out why plant pollination by birds and insects is crashing around the world.

They found that even when it meant a much longer trip, the hermit hummingbirds kept to the forest, rather than cross land cleared for farms.

The findings are published in the journal Biology Letters and shed light on a long-standing issue in ecology: the fragmentation of ecosystems by roads and development.

The scientists say the findings suggest that isolated patches of forest may ultimately result in species decline, because birds that normally spread pollen won't cross developed land to visit them.


This composite photo from Oregon State University shows green hermit hummingbirds at Las Cruces Biological Station, San Vito, Costa Rica, that were part of a study on how habitat fragmentation affects birds that pollinate plants. The red arrow indicates a tiny transmitter used to track the birds. Scientists from Oregon State University glued tiny transmitters to hummingbirds in Costa Rica to figure out why plant pollination by birds and insects is crashing around the world. The photo at upper right is by Matthew Betts. The photo of the transmitter is by J. Miller. [AP Photo/Oregon State University]

very interesting artcle Patricia. I have to say that it did concern me that the transmitters tho tiny are being glued to the birds.

Penny
Niagara Falls, NY
USDA zone 6a/6b
Heat zone 4
Sunset zone 39

I didn't realize the technology had advanced far enough to get transmitters small enough to go on hummingbirds. That's pretty exciting. Maybe they will get smaller yet in the coming years, and it will eventually be possible to track migrations of small hummingbirds like the Rufous and Ruby-throated.

My guess is that they probably use a glue that will biodegrade and that the transmitters fall off harmlessly after a certain amount of time. At least, I hope so! Researchers really should, and usually do consider the well being of their wild research subjects. We can only hope these scientists have thought it out properly and are mindful of the well being of the birds. If not, they should have their permits taken away.

As for the content of the article, I suppose the effects of forest fragmentation must be different on various species of hummingbirds. It's obviously quite a complex world we live in. What humans do to change the environment can have varying effects on different species and alter the natural balance in ways we can seldom predict.

I don't know if these sorts of studies have been done on Ruby-throats, but it strikes me that Ruby-throated hummingbirds seem to do fine in the suburbs, and even in the cities, moving freely from one patch of woods to someone's garden and all around. My guess is they aren't as severely impacted as the Hermits described in the article, but I don't really know for sure. Are these Hermits migratory? I'm assuming not, so maybe they are less tolerant of variability in their environment. I wonder if anyone has done any similar studies on the habitat requirements of Ruby-throated hummingbirds. Even for familiar species, there's so much we don't know. I'm glad there are scientists taking the time to assess the impacts of human influence on various species. They sure have their work cut out for them, and not nearly enough research dollars to go around.

Although knowledge comes slowly, the more we learn, the more we can minimize our impact on the natural world around us. Kudos to the field biologists!

An interesting article. However, I believe it gives only a small part of the over all picture. For hummingbirds, there are certainly species that will be harmed by clear cutting of forested lands. Not a good thing. Still there are several species, including Rufous-tailed and Steely-vented that benefit from forest removal. In some respects, they are like grackles that move into cleared land. Nevertheless, the diminishment of one species cannot be compensated for by the expansion of another. Each species of mammal, bird, reptile, amphibian, insect, arachnid, and amoeba has its place on the planet Earth.

Kristin, there is indeed a protocol to the handling of birds for research. See http://www.nmnh.si.edu/BIRDNET/GuideToUse/. I don't know much about the transmitters or the manner of their use, but I suspect that they are glued to feathers and will fall off as the feathers are molted. I am somewhat concerned about the functionality of the birds wearing these transmitters, but again, I don't know anything about the way they are used.

The Green Hermit is a large hummingbird and it can probably carry the transmitter easily. I doubt such a device would be usable on our migratory Ruby-throateds, which are much smaller and which won't remain in an area for more than a few months. By Federal regulation, our studies of North American birds cannot add more than 3% to the normal species weight of the birds we study and all projects must be scrutinized by other biologists and must be individually authorized.

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Nancy L Newfield
Casa Colibrí
Metairie, Louisiana USA
USDA Zone 9

Thanks for the protocols link. Not being a field biologist, I wasn't aware of these specific protocols, but having worked with scientists, and having been involved in field work myself many years ago, I knew that there were standards designed to protect wild research subjects from harmful meddling. One hopes the researchers are being mindful with their transmitters.

What I didn't realize is that transmitters had gotten small enough to attach to a hummingbird of any sort. I thought they only worked for something the size of a medium passerine, and so I was surprised to see them attaching a transmitter to the wing of a Hermit. It just shows I haven't been paying attention to advances in technology. It gives me hope that in the coming years these transmitters may get smaller, yet, and may eventually become practical for smaller hummingbirds like Ruby-throated and Rufous, etc. Cool to think that some day we might be able to track them, too.

You're right to point out the limitations in the study, but all studies are limited. It occurs to me that although this study referred to disruptions with feeding, it apparently did not examine effects on breeding. It also focuses on just one species. As you point out, Nancy, requirements among species vary, some helped, and some harmed by the clearing of forest. Migratory birds present other issues. It's sobering that these are complex, global systems that humans are disrupting, but political decisions tend to be more local and not globally coordinated. Meanwhile, additional scientific knowledge comes slowly, in little bits. Even though some studies may focus on greater numbers of species, the entire picture still remains complicated and must be pieced together.

I'm always pleased that people are studying these things and learning more, but I can only wonder how we can best translate all of this information into sound environmental policy. Help one species, hurt another--what's a human to do? Preserving as much as we can of remaining large natural areas is certainly a good bet, but other decisions might not be so clear. Understanding ecosystems remains a work in progress, I guess, but we're running out of time on a lot of species and habitats, and studies like the Hermit one are just one tiny, tiny piece.

It's kind of scary that we humans are playing God. Let's hope we can use our growing scientific knowledge to make the best possible decisions, and find the political will to be better stewards of the planet.

Kristin, Green Hermits weigh about 6 grams, roughly twice the weight of a non-migrating Ruby-throated so transmitters don't have to be made much smaller than those to be usable on Ruby-throateds. However, I suspect that those tiny transmitters might have a limited range so that reception would soon be lost when the bird moved out of range, which is inevitable on a migratory bird. Additionally, it appears that the antenna would hamper copulation. Perhaps the study was done outside the breeding season or the transmitters were only placed on males. The photo wasn't very detailed, but I thought the transmitter was on the bird's back rather than the wing. Just speculation, but I don't know how a hummer could fly with any additional weight on one wing.

I can see how forest fragmentation might create havoc for a species like the Green Hermit. In their breeding system, only one male in a lek of 20-30 individuals mates with all the visiting females. Inbreeding would result much more quickly than it would for a species that had a breeding system like that of the Ruby-throated.

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Nancy L Newfield
Casa Colibrí
Metairie, Louisiana USA
USDA Zone 9

Yeah. I don't know what I was thinking. It makes a lot more sense it would be on the back instead of the wing--especially a hummingbird, the way they beat their wings.

Interesting stuff. I forget what book it was I read about someone in the early days of transmitters following a thrush across the United States, driving in his car. He had to stay pretty close, with an antenna sticking out of a hole he had cut in his roof. He kept up by doing zigzags on roads while the bird flew straight. I think he lost it once but then made a guess where it might have been and was miraculously able to pick up the signal again. I think there was also some wild stuff at the border crossing into Canada. I'm not remembering the details very well, but I remember it was a great read--quite a zany and funny story. The poor guy hardly got any sleep as the bird spent hours flying during the night. It was a total miracle that he was able to keep up, but through sheer grit and perseverance he was able to document the bird's migratory flight path.

I think I have that book upstairs somewhere. I should find it and reread those passages. It was a hoot!

Nancy and I have discussed before the idea of transmitters for hummingbirds and the limitations that their small body size and mass would place on any such equipment. Anything capable of sending a signal trackable by, say, satellite would be impossibly large for a hummingbird--the power requirements alone would mean a battery pack weighing as much or more than the bird, else the signal couldn't be picked up by the satellites.

However, a separate idea occurred to me the other day, which might actually be feasible at some point - not for migration tracking, but at least for tracking individual birds for site fidelity. RFID tags, which are extremely tiny, lightweight pieces of electronics that are used for inventory control in stores, checking out of library books, and so forth, might be possible to incorporate into a band. An RFID tag can be made exremely tiny (no wider than a human hair, and about the same length for the smallest versions I know of) with a tiny antenna also no wider than a hair and a faction of an inch long. Even "basic" tags today can be made the size of a grain of rice, which is closing in on attachable to a bird.

These tiniest tags can be read by a tag-reader within about ten inches. So in theory, for birds which are trap-shy after initial banding, an RFID reader hung on top of a hummingbird feeder could "read" the bird's tag as it came in to feed and confirm its identity.

In studying feeder usage, such a tag could also help monitor how often individual banded birds visited all the feeders at a site, for instance - particularly useful if the site has lots of feeders scattered over a large area. Just zero-out the RFID readers at a set time (say, dawn), hang them on the feeders, and collect the data after dusk.

Of course, it all presupposes that you can catch the birds initially, and this kind of tracking means you can't gather all the other data (measurements, for instance) that you can get from re-trapping a banded bird. But when tags this size hit the nickel price point, it's certainly something which might be feasible.

Something to think about for the future...

Kevin Morgan
Baton Rouge, LA

Sorry, I don't really understand all the ins and outs of these transmitters. Are there non satellite means of tracking that would allow a smaller transmitter? Dumb question, maybe, but I guess I don't really understand how these various methods work. Does a transmitter have to be larger and more powerful to be picked up by a satellite? Could it be smaller (maybe even sufficiently small for a hummingbird) and less powerful, yet be picked up by a different receiving method with more limited range--say, a mile or two?

I've been with falconers who had those silly looking TV antenna type receivers that they could use to track their falcons. I never really understood how they worked. The range was pretty limited, and, of course, the transmitters on the falcons were way too large for hummingbirds. Then again, this was years ago, so I imagine the technology has improved quite a bit since then.

The bar code tag certainly has its own potential, but I still can't help dreaming about being able to track migrating hummingbirds, and wondering when or if the technology might some day get good enough to do just that.

If we could track 'our' hummers that we are sure are the ones that return, because they have sat on the same branch for 3 years straight, those in the north could possibly contact them and get them to visit sooner and for longer periods longer!
'Beam me up Scotty'!

Hmmm. Let's see. While I'm dreaming about tiny, cutting edge technology....

How small are the latest in teeny, tiny little speakers? Maybe they could be pre-programmed to whisper "time to go north, time to go north, time to go north..." at just the right time. Unfortunately, I'm still hung up on how to make them understand what we're saying...Of course, even if they did understand us, those little free spirits would probably do just as they pleased anyway!

The negative effect of forest fragmentation is pretty well known here in North America. All a person needs to do is look at breeding bird atlas maps and see where particular breeding birds occur. Many species, about 1/2 here in Southern New Jersey, require large tracts of forest if they are to occur.