Recording nest temperature provides data used to help understand the breeding strategies and outcomes of shorebirds in the Arctic.
Tinytag data loggers are being used in the Arctic to
monitor the nest temperature of breeding shorebirds.
Robust Tinytag Plus 2 TGP-4020
data loggers used with thermistor probes will be
located at 11 sites in 2016 throughout Greenland, Canada, Alaska,
Sweden and Russia. Several hundreds of nests have already been
monitored in Greenland and Canada in previous years.
The researchers are focusing on small
shorebirds, also called 'sandpipers', and especially
'Dunlins' and 'Sanderlings' in
Greenland. Dr Olivier Gilg, Associate Researcher
at the University of Bourgogne (Dijon, France) and Chairman of the
Arctic Ecology Research Group (GREA, France) is coordinating the
Team using the Tinytags. He comments, "A colleague
started using the Tinytags in Greenland in 2007 and they have many
advantages over the traditional and time consuming visual
observations we did before."
The probe is placed between the four eggs (the
shorebirds studied lay four, or more rarely three eggs) with the
Plus 2 data logger itself hidden about 50cm away: when the bird
sits on the nest nothing is visible. The loggers are set to record
once per minute, enabling monitoring for the entire three
week incubation period, compared to traditional studies
when it was necessary to spend time walking long distances every
one or two days to check the fate of the nest. This also allows the
Team more time to find additional nests, and more importantly,
reduces disturbance including predation risk because foxes, raven
and other 'egg lovers' can sometime follow the researchers' tracks
to find the nests!
There are several key pieces of information that the Team can learn
from the recorded data, using a standardized method for all sites.
Firstly, they can document the outcome of the nest and primarily,
the date of this outcome: if the nest produces young then
the temperature declines and becomes more chaotic for 24h before it
is left (young birds are drying for around 24 hours after
hatching before they leave the nest). If the nest falls victim to
predators, the temperature drops dramatically from one
minute to the next since the nest is abandoned and the
birds do not come back to incubate an empty nest.
For species with different breeding strategies (either one or
two adults incubating), the recorded data provides details about
this strategy: if there are two birds, they take turns and
the temperature drops only for short periods; if one bird
incubates alone then it has to feed, mainly between 9am and 5pm for
around 10 minutes in every 30, and the temperature will
Finally, using spreadsheet filters developed by Dr. Gilg and
colleagues, the number of recesses (periods when the nest
is not incubated) per day can automatically be extracted along with
the total daily duration of these recesses. This allows
the researchers to test other ecological hypothesis related to
predation: for example, birds that are leaving the nest more often
or longer should be more impacted by predation. Because other
information is also available about these birds (their history in
some cases; their body conditions in most cases; their wintering
grounds eventually using isotopic concentration of winter grown
feathers, etc.), it is possible to understand how all these
parameters impact (or not) upon their breeding
Dr. Gilg concludes, "Compared to previous methods
requiring regular visits, the Tinytags allow us to collect a large
amount of accurate data, and also reduces the disturbance of the
birds and the predation risk. Placing the logger in the nest only
takes a few minutes (once) and it will then continue to record data
during the entire incubation period."
The image shows 4 eggs with one probe in the middle in a
Sanderling nest, from NE Greenland.