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Archive for June 29th, 2011

Jennie listens intently for the high pitched chirp of a radio signal.

Last year on Metinic, a new question started being researched; “where do the Terns go to fish?”  Terns take shifts incubating chicks and foraging for fish to bring back to their mate or young.  Last year we started performing “foraging flight surveys”.  This consisted of watching to see what direction Terns return with fish from, or what direction they take when they leave, and then taking a compass bearing on that point.  This doesn’t tell us where they are getting the fish from, but at least we know where to look! The data from last year was overwhelmingly unidirectional towards the north west.

This year we are expanding the research to include a telemetry aspect.  Telemetry, put simply, is putting a radio transmitter on an animal to be able to track its movements with an antenna.  A couple weeks ago five Arctic Terns and five Common Terns were outfitted with small radio transmitters, each with a specific frequency that we can use to identify individuals.  Then their breast feathers were dyed a deep red, so that they can be identified within the colony.  The dye allows us to confirm that the birds are still incubating and our efforts have not caused abandonment, as well as identify an individual as a radio bird in flight.

Increasing antenna height even a few feet can tremendously help signal reception.

Twice a day we raise our antenna as high as possible and rotate it in slow sweeps of the island hoping to pick up the radio signals and establish presence or absence of the individuals within the colony.  We have also been experimenting with signal range, and whether we can get bearings on Terns leaving the colony for foraging.

These efforts have been paired with USFWS staff using a similar antenna system on a boat.  The hope is that the antenna on the boat can pick up a signal from a bird leaving the colony to forage, and then staff members can radio track the bird to see where it is going to fish. If radio birds are not within signal range, then the direction from the foraging flight surveys can be used to try to find a foraging flock.  Hopefully we will able to get information on how far these birds need to go to find food, and how long that takes them.

If we are able to establish where foraging Terns are going day after day to find fish for their chicks, we can then help to protect this vital resource.  If this resource is not protected, Terns will have a much harder time finding schools of fish to feed upon, which could lead to weaker fledglings or birds who choose not to reproduce in order to save energy for migration.  One current concern is the establishment of wind turbines in vital feeding areas.  We welcome a push towards more sustainable energy practices in Maine but a lot of consideration needs to be put into placement.  Hopefully we will be able to gather enough information to help assist that tough decision making process.

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