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 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,
using a total of over 300 loggers. Several hundreds of nests have
already been monitored in Greenland and Canada in previous
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
The probe is placed between the four eggs (the shorebirds
studied lay four, or more rarely three eggs) with the Plus 2 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 fluctuate.
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: e.g.
birds that are leaving the nest more often or longer should be more
impacted by predation. And because other information is 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 success.
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.