Thursday, November 19, 2009

Batting average

Here are some photos from a field biology camp I went on in September. It was held in the Strathbogie Ranges, in northern Victoria. I was in the bat group. Our project was to work out whether higher temperatures resulted in more insect activity and therefore more bat activity. We trapped the bats using a harp trap, which looks like this. The frame is strung with fishing line, which the bat flies into. It bounces off the trap and into the canvas bag below.

The first two nights of the camp were very cold (down to zero degrees), so we spent a lot of time walking around in the bush late at night but catching nothing. This was great preparation for a major part of real field work: dealing with frustration and disappointment. Then it warmed up, and we woke up one morning to this miraculous sight.

We caught two species of microbat: the Southern Forest Bat and the Little Forest Bat. It's difficult to tell which is which from the photos, because the two species look very similar, and are distinguished by (among other features) subtle differences in their fur and the morphology of the tips of their penises.

Here's an echidna I ran into one day. I took a video (pasted at the end of this entry) because echidnas' rolling gait always makes me laugh. Echidnas are mammals, because they produce milk, but unlike most mammals, they lay eggs. This is not their only reptilian feature. They also have a reptilian-style pelvis, which explains why they walk with their legs splaying out to the side, like a lizard. However, their archaic physiology shouldn't be taken as a sign of low intelligence. According to our lecturer, Kath, laboratory tests have shown that echidnas have the intellect of a domestic cat. I probably wouldn't want to stroke one on my knee, though.

However, I suspect that Kath might. Here she is demonstrating how to capture an echidna bare-handed. Understandably, the echidna was not happy. Being an intelligent creature, it communicated its disgust in a way it was sure humans could understand: by pooing all over Kath's pants. This was fortunate because one of the groups was collecting mammalian faecal samples, and was able to scrape the poo into a zip lock bag.

Here's a Mountain Brushtail possum, or bobuck, who is being measured and having his details recorded. The possum looks a bit dopey because he has just been sedated. This possum would later wake up to find that while he was out of it, he had gotten a tattoo. Fortunately, it wasn't a dolphin, or text from Kabbalah. Possums aren't that stupid. The tattoo was an identification number so he can be included in a long term population study of bobucks in the Strathbogies.

Here's a male Superb Fairy Wren in breeding plumage. Another group was capturing these birds with a fine net strung between trees, and fitting them with leg bands. This was so individual birds could be identified, in order to give an idea of their social structure. I've seen groups of fairy wrens around and always assumed that they consisted of one colourful male and his harem of brown females. But in fact each group consists of just one breeding pair. The other brown individuals are subordinate males, often offspring from previous years, who stick around to help the breeding pair raise their young. Other females are chased out the territory.

Continuing the theme of previous blogs about promiscuous birds, fairy wrens have one of the highest proportions of illegitimate young of any birds - about 70 per cent of offspring come from extra pair matings. Male fairy wrens have been observed picking up yellow flowers in their beaks and offering them to females in other territories in the hope of gaining matings. This kind of behaviour is known as the 'sneaky fucker' strategy, which is the official biological term. So many words in biology have complicated Greek or Latin roots. I'm all for this kind of simplification.

Here's a small-eyed snake, the bite of which will cause kidney failure. Luckily, this was only a baby.

I saw my first wombat on camp. It had a bad case of mange and was caught in the headlights for a few seconds as we drove between bat study sites. However, wombats were active around our camp, as this great photo shows. This picture, along with a lot of the better shots in this blog, were taken by my fellow bat-person, Stan.

I'll leave you with this message (the first video), spoken in bat by one of our subjects. The clicking sound is a sonar hunting call made by the bat. Bats use echolocation to 'see' insects in the dark. The call would not usually be audible to humans, but we can hear it through the Anabat sonar detector sitting on the table. It translates the sound into an audible pitch. Unfortunately, the detector does not, as my Mum suggested, translate into English. I'll let you decide what this bat is saying.

video video


Benjamin Law said...

Rhianna, this was really terrific. If you had been my high-school biology teacher — offering fun, educational, adorable lessons in wildlife — maybe I would have been more engaged in science ... and a whole less stupid.


P.S. I can get an echidna at a pet store, right? They seem pretty awesome.

Rhianna Boyle said...

Ben, I can just see you toting an echidna around in an oversized handbag, like Paris Hilton with her chihuahua.

Vijay said...

Very informative write-up. I enjoyed it.
I observed only one blue headed Superb Fairy Wren among a group of several birds at the Melbourne Museum’s indoor forest. I thought only one male was there. Your blog gives me some idea.
Still, a doubt arises in my mind... if each group of Superb Fairy Wren consists of a breeding pair, and some subordinate males, then there should be some imbalance of gender in Superb Fairy Wren’s population (with many males to one female in a group).
Any clue?

bert said...

Hi Rhianna, I live around the corner from Kath's field station, at Boho South (Kath's an old, old friend, we used to share student houses together). Anyway, I'd like to put your photo of the small-eyed snake on our Landcare flora & fauna web pages, if I may (acknowledging you as 'author'). Kath told me that the species was recorded, but I didn't know a pic existed.

Would that be OK with you?


The url is