By Ben Neary
NMWF Conservation Director
As New Mexico becomes increasingly warmer and drier, biologist Shayne Halter is working on ways to gauge the health of hummingbirds that move through the state.
New Mexico is the summertime home of populations of black-chinned and broad-tailed hummingbirds, among others. Late in the summer, Rufous and calliope hummingbirds will pass through the state. All of the different types head south to Mexico during the winter.
Hummingbirds feed on plant nectar and insects. Changes in climate and land use are resulting in fewer blossoming plants in many areas. That can leave the birds facing hard times in New Mexico.
Halter is working on a Ph.D. in biology at the University of New Mexico. His research focuses on assessing hummingbirds’ body fat, measuring their metabolic rate and looking at how they use torpor – a sleeplike state during which their body temperature drops – to control their energy consumption.
Halter is the featured speaker at the New Mexico Wildlife Federation’s free “Wildlife Wednesday” presentation for October. His talk will start at 5:30 p.m., Oct. 9, at Marble Brewery’s Northeast Heights Taproom, at 9904 Montgomery, Blvd., NE, Albuquerque.
Biology is a second career for Halter. He was in the U.S. Air Force for 24 years where he served as a navigator in C-130s – huge turboprop transport airplanes. He was stationed at Kirtland AFB in Albuquerque when he retired.
At UNM, Halter is working on his Ph.D with Professor Blair Wolf, a former board member at the NMWF. Halter also works with current NMWF board member Carlos Martinez del Rio, a retired biology professor who most recently worked at the University of Wyoming. Both Wolf and Martinez del Rio live in southern New Mexico, on the southern flank of the Gila Wilderness.
Two years ago, Halter obtained several permits from various wildlife agencies that allowed him to capture hundreds of hummingbirds as they passed through Wolf’s property in Mimbres. Once Halter assessed the birds’ health, he released them, keeping careful records of their condition.
Halter trapped the birds by putting feeders in wire cages he constructed. He released lines to close doors on the cages when he saw the birds he wanted.
“I have access to a machine, it’s kind of like an MRI, it’s called a quantitative magnetic resonance scanner,” Halter said. “And the machine weighs about 400 pounds. It’s basically a big, huge magnet, and then there’s all the computer stuff that goes along with it.
“You basically put the bird into a tube and you shove the tube into the machine and it takes about three minutes and it actually gives you the lean mass, fat mass and water content of that bird in grams,” Halter said. “It’s just amazing.”
Halter’s approach yields precise information about the birds’ condition.
“That’s one of the cool things about my research is that not too many people have done that before – have actually been able to directly measure fat in hummingbirds,” Halter said.
Typically, researchers have been limited only to weighing captured hummingbirds to try to assess their condition, Halter said. Merely weighing the birds gives figures that include whatever food the birds have in their crops as well as whatever feces they’re carrying.
“It’s not a good measure of how much fat they have,” Halter said of weighing the birds. “So with this machine, we’re able to actually measure the body fat, and do it without killing the bird.”
Assessing the body fat of the hummingbirds provides critical information about their condition, and their fitness for making their long migration.
Halter also studies how hummingbirds use torpor to maintain their critical fat reserves.
“Hummingbirds can use torpor anywhere,” Halter said. “They typically use it more while they’re migrating and more just before they migrate.
“Hummingbirds kind of run on fat, that’s their fuel,” Halter said. “They put on extra fat to migrate, and one of the ways they build extra fat is they use a lot more torpor so at nighttime they’re not burning fat so they can just keep building it on. Torpor can happen pretty much anytime in hummingbirds, but it changes pretty much with the seasons.”
Halter is using his data to develop a model that allows accurate estimates of whether a bird is going to go into torpor, how long it’s going to stay in torpor and how much energy it will save in that state.
Halter’s research also includes studying hummingbird feathers to assess where they’re coming from and how far they’ve flown. He also takes detailed measurements of the birds’ metabolic rates.
“So, what impact is this research going to have? It’s going to be tied to climate change and land-use change and being able to measure hummingbirds and be able to tell what kind of condition they’re in,” Halter said.
“It’s the idea that you can actually catch a hummingbird, and you can get an idea of what its body condition is. And if you know how far it’s flown, you have an idea of what challenges it’s up against,” Halter said. “And hummingbirds, their food sources are pretty unreliable. They eat nectar, which is from seasonal flowers.
“When they migrate, they kind of connect stopover sites,” Halter said. “They can’t go very far nonstop. So some of those stopover sites that they stop at don’t have any nectar, and they have to either move on or they starve. And this research is going to be a way to be able to get a really good idea of what condition any hummingbird is in when you catch it.”