Today was my first day mist netting. For those of you who think this is a cush job (I'm not mentioning any names here...), we got up at 4:15 am and got home at 4:15 pm. My advisor says this was an easy day and that we will have to get up much earlier tomorow! Actually, getting up wasn't bad at all now that it is not so cold in the morning.
There was a lot to learn-- setting up mist nets (I think I'll definitely have more arm muscle after a few days with a sledge hammer), extricating birds from the net, bleeding the bird, banding, assessing fat deposits, age, sex, presence of a brood patch or cloacal protuberance etc. This is what our field table looked like:
I saw my second ovenbird (above), which we promptly released as it is just migrating through and so not useful for our data.
Bleeding birds is not nearly as difficult as I imagined. The standard technique is to poke the brachial vein with a 27 gauge needle and then suck up 0.1ml of blood using a capillary tube. Afterwards, a piece of cotton is used to apply pressure briefly. I'm told there is very little chance of a bird bleeding out this way. For larger volumes, it is necessary to draw from a jugular, where there is substantially more risk of exsanguinating your research subject. However, to test for West Nile virus antibodies 0.1ml of blood is more than sufficient (and interestingly, as much as 10% of the total blood volume on some of the smaller species such as chickadees). Here I am drawing blood on a female house sparrow. It only took me a few tries to feel fairly proficient at it. It was certainly much easier than learning to draw blood on a cat or dog!
2 comments:
I would never in a million years think that drawing blood from a bird would be easier than from a dog or cat!
Agreed. I think it is because you are basically just pricking the vein and then using a crit tube. I think it would be much, much harder if you actually had to use a syringe to get the same or a larger volume of blood.
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