June 14 - geolocators

View over the Brooks Range

Another long day today, nine miles hiked from 10am until 5pm – it is always a fun time spending over 8 hours walking in thigh waders. A second gorgeous day in a row, the sun has been out for over 26 hours now, and the winds still low – both things that we wouldn’t have thought possible just a couple days ago.

 A Semipalmated Sandpiper egg that was found outside a nest - unfortunately a lost cause.

Visibility was at least 50+ miles today over the Brooks Range – crystal clear air with no visible taint from humanity. Likely the same mother Caribou and her calf were seen again today at pretty close range, and an Arctic Fox paid us a visit in camp while we were eating dinner – thanks to the nice weather we can now enjoy the novel experience of having the door of the tent open while we eat.

Another visitor to our tents are these charismatic grumpy-looking Arctic Ground-Squirrels

The first three Dunlin nests of the season were found today, among 20 new nests overall, our biggest haul of the season yet, and the first day that everyone discovered at least one nest! Today also is the first time that anyone had seen any of the Dunlin on the study area that were equipped with geolocators two years ago. Geolocators are small square microchips that are attached to a plastic flag on a bird’s leg in our case, and stay on the bird much like a band does. However, the geolocators have a primitive light sensor in them and a battery that runs them for a couple years, enabling the sensor to detect what time the sun rises and when it sets by measuring ambient light levels.

A poor picture, but this shows the individual with the geolocator attached! The silvery part peeking up over the large double-wide green flag is the microchip part.

Here is a closeup of a geolocator (Source: http://www.birdtracker.co.uk/)

These are not incredibly accurate, within ~150km according to one company that sells them, but on a global scale that is pretty good! Since Dunlin return to the same area to breed each year, like many of our focal species, we can catch the birds in subsequent years and remove the geolocator, and then see where these individuals go when they’re not breeding here!