The impact of transmitters

Dr Phil Battley, from Massey University, discusses how both internal and external satellite transmitters might affect godwits. He shares that internal transmitters worked better than external transmitters (backpacks). He also adds that a future study will look at long-term impacts of internal transmitters on godwits.

Transcript

Dr Phil Battley

Obviously, doing a surgery on a bird is a very invasive procedure, and when we’re doing this research, there are two stages of permitting that’s needed. One is an ethics approval from a university or body, another one is a permit from Department of Conservation, and we have to be sure in ourselves that what we’re trying to do has the best chance of succeeding.

It’s also an unknown technique to try these on these birds, so we went into not really knowing quite how it would pan out. We were very happy when it did go as well as it did. Having said that, there can be problems. We did have a couple of birds die during the surgery. Things were going well and then something happens. Was it something about how we did or was it something about the birds?

The person we had doing the surgeries is the most experienced person in the world. He works for the US Geological Survey in Alaska, and he has done between 2 and 3000 surgeries putting transmitters into a wide range of birds, 30 or 40 species, so we knew we had the best people for the job, and we were sure that we were doing things as well as we could. We also had the best bird vet in New Zealand as well.

But it’s one thing to put the transmitters on and then have the birds go away and do their thing and then we need to have a look at everything and say, is there any suggestion that these impacted on the survival or the performance of the birds? For the backpack transmitters, it’s clear that migration performance of the birds was hampered by them, so we wouldn’t now recommend that technique for birds making this fast endurance flapping flight. Anything we put on the outside of a bird is going to interfere with airflow and increase the drag so it’s much harder for the bird to fly at the same speed than it would have before – it uses a lot more energy.

I think the external transmitters, even though they are lighter and in theory should be better for the bird, had a bigger impact on their migration than the internal ones did. The implanted transmitters is a little bit harder to assess because we can’t actually see what the birds are doing at all stages of the cycle. One of the things we will be doing is evaluating do we think these have any longer-term impact on the birds.

Acknowledgements: Pete & Judy Morrin Productions