Bugs of the field 2014: dragonflies & spiders

Whoops – I forgot to post these for a while. Here are some photos from last summer of dragonflies and spiders: charismatic, often beautiful, and highly-effective hunters that make me glad I am much bigger than they are.

Male white-faced meadowhawk

Male white-faced meadowhawk

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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.

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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

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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.

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