Do birds have a sense of smell?

Not too long ago, the generally-accepted answer to this question would have been: “Not really—a few birds do, but most don’t.” This was largely based on the observation that most birds have very small olfactory bulbs in their brain relative to their overall brain size. As we observe bird behavior, however, we are are increasingly realizing that most birds can and do use smell regularly, often for very important things.

Let’s begin with the birds that have been known for a long time to use smell. Kiwi birds are unique in having their nostrils on the end of their bills, rather than close to the base of the bill like all other birds. Kiwis stick that long bill into the soil and use their nostrils to sniff for insects and worms.

Brown Kiwi chick. Photo by Smithsonian's National Zoo*

Brown Kiwi chick.
Photo by Smithsonian’s National Zoo*

It makes a lot of sense that kiwis have a good sense of smell, even if you think that birds in general don’t, because kiwis seem to have evolved to be the avian version of a small fuzzy mammal. Kiwis evolved on the islands of New Zealand, where the only mammals were bats. The small-brown-fuzzy-nocturnal-snuffling-in-the-dirt-for-worms niche was open for the taking, and kiwis—flightless, nocturnal, and covered in long thin feathers that are highly reminiscent of hair—took it. A good sense of smell goes with that niche.

Continue reading

The beauty and the beast; or, a tale of two moles

The Beauty

Technically, golden moles are not true moles—they are more closely related to tenrecs than they are to true moles—but golden moles are small, burrowing, insect-eating mammals that, with their streamlined heads and powerful digging claws, have converged to look a lot like true moles.

With at least one key difference: golden moles shine. They shimmer. They iridesce.

Juliana's golden mole. Photo from ARKive.

Juliana’s golden mole. It’s a bit hard to see the iridescence in photographs, but it’s there. Photo from ARKive.

The hairs on a golden mole reflect light in such a way to give the animal a sheen, ranging in color from gold to green to purple. In the museum where I work, we have some preserved specimens of golden moles, and they are remarkable to see: their fur shines and shimmers like the coat of a child’s stuffed toy unicorn.

Continue reading

Seeing song: an interview with a partially deaf ornithologist who studies bird song

Alma Schrage is a recent graduate of UC Berkeley and a research assistant in the Bowie lab in the Museum of Vertebrate Zoology. Over several years I have watched her become an ornithologist. In this interview she discusses her research on bird song and how it has been affected—or not—by being partially deaf.

Alma in the field. Photo courtesy of Alma Schrage.

Alma in the field. Photo courtesy of Alma Schrage.

Why study bird song?

It’s interesting on several different levels. If you’re interested in cognition and behavior, bird song provides so many different things to study. You can also study how vocalizations tie in with genetics, morphology and such to help provide a fuller picture of the bird, or you can study the factors that drive development of bird song such as different acoustic environments, and selective forces on calls and songs.

Continue reading

Nudibranchs defend themselves with their food

Nudibranchs, or sea slugs, are descended from animals with protective shells like those of modern snails. Nudibranchs have lost that shell, leaving them potentially vulnerable: squishy morsels in an ocean full of hungry things. But nudibranchs have some tricks to avoid becoming someone else’s meal: they use their own food to protect themselves.

Hermissenda crassicornis may not have a shell, but he is well-defended. Photo by M. LaBarbera

Hermissenda crassicornis may not have a shell, but he is well-defended.
Photo by M. LaBarbera

One trick is to steal the defenses of your prey. Many nudibranchs eat stinging animals like hydroids and anemones. These animals use specialized stinging cells to catch their own prey and to defend themselves.

Hydroids. The stinging cells are on the ends of the long tentacles, waiting to catch prey. Photo by M. LaBarbera

Hydroids. The stinging cells are on the ends of the long tentacles, waiting to catch prey.
Photo by M. LaBarbera

Continue reading

Featured paper: five warblers, lots of tornadoes, and a mystery

Male Golden-winged Warbler. Photo by Mark Peck*

Male Golden-winged Warbler. Photo by Mark Peck*

This story begins when Streby et al. (2015) decided to track Golden-winged Warblers during their annual migration. We know that lots of birds migrate, but for most of them, we know surprisingly few details about that migration. Often we know generally where they go (to a specificity of, say, “somewhere in South America”) but not exactly where; rarely do we know what paths they take to get between wintering and breeding grounds. This kind of information is especially important for birds of conservation concern, since to protect a migratory population, you need to protect its wintering grounds and migration route as well as its breeding grounds.

The researchers relied on technology to tell them where the warblers went when they migrated. There are several different ways to track animal movements; in this case, researchers used light-level geolocators, which record the amount of light hitting the geolocator. Collected over time, these light intensity measurements allow researchers to calculate where the geolocator was, based on things such as day length. This location information isn’t as accurate as the data you would get from a GPS logger, but the light-level geolocators have a big advantage over GPS loggers: they can be much smaller, so you can put them on tiny birds like Golden-winged Warblers. A Golden-winged Warbler attached to a heavy, clunky GPS logger would not be migrating anywhere.

Continue reading