terrestrial mammals

Pas de contenu pour le moment

Polar bears live in a challenging environment for human beings, and getting close to them is not without dangers. Wildlife tracking using Argos PTTs has thus enabled us to know more about them.

The polar bear (Ursus maritimus) is heavily dependent on sea ice, since they feed on seals (ringed seals and bearded seals) they catch when they surface to breath or haul out.  Satellite telemetry using Argos has been the key to learn about the wanderings of the polar bears.  The early methods required flying in an aircraft to track the bears, which was not only inefficient but also dangerous for those doing the tracking.  With the advent of satellites, we can examine the characteristics of the habitats that the bears use, how far they move each day, how often they swim and how far, and critically in a rapidly changing Arctic, how the bears are responding to sea ice loss.

An adult male polar bear with an ear tag Argos PTT (Credits A. Derocher)
An adult male polar bear with an ear tag Argos PTT (Credits A. Derocher)

The core of the research and monitoring program at the University of Alberta has used satellite telemetry on polar bears for decades using Argos PTT collars deployed on adult female. By tracking adult females, we know those with young cubs fresh from the den use different areas than those with older cubs.  Furthermore, females in mating condition use different areas yet again.  The main benefit of the collars is that they can provide up to six locations per day for one or two years.  In recent years, ear tags have also been used to expand our insights on adult male and subadult populations, which have a different behaviour than adult females. The ear tags with tiny batteries only transmit for a few months, but since collars do not fit on male polar bears, and can’t be used on growing individuals, using both approaches yield insights into the world of the bears.

Locations of adult female polar bears on June 4, 2018 tracked by U. Alberta
Locations of adult female polar bears on June 4, 2018 tracked by U. Alberta
The ear-tagged ones tracked since May 2018. (U. Alberta)
The ear-tagged ones tracked since May 2018. The ear-tagged bears remain closer to shore than the collared females that wander over much of Hudson Bay (U. Alberta)

As the Arctic changes, one of the key monitoring parameters is the duration of the on-ice period.  A pregnant female can fast for up to 8 months and give birth to a pair of cubs and nurse them up to about 10 kg each before returning to the sea ice to feed again but an earlier break-up can reduce cub survival.  Such a fast isn’t possible for subadults that are rapidly growing, less experienced at hunting, and thus have less stored fat. In addition, adult males focus on mating in the spring, and looking for love happens at the expense of eating.  The net result is that subadults and adult males can fast for shorter periods than females.  How long they can go is a focus of our field research: the satellite data are used to tell when the bears arrive on land as the ice breaks up, and when they leave again to resume their life on sea ice.

The data collected on the bears also helps wildlife managers make decisions. All analyses suggest that we’ll lose many populations as the sea ice disappears for too long in a given year and the bears are no longer able to balance their feasting and fasting.  However, we also expect the bears to persist to the end of the century in the High Arctic of Canada and Greenland.  It’s a challenging time ahead for polar bears, but knowing them better should help.

Photo featured: Collared female with two cubs. (Credits A. Derocher)

References

Dag Vongraven, Andrew E. Derocher and Alyssa M. Bohart, 2018: Polar bear research: has science helped management and conservation?, Environmental Reviews, DOI: 10.1139/er-2018-0021

Polar Bear Science http://polarbears.biology.ualberta.ca/

Andrew Derocher on twitter https://twitter.com/AEDerocher

An Argos-tagged juvenile whale shark swims through the waters of Panaon Island, Southern Leyte (Credits LAMAVE).

31.07.2018 Animal tracking applications Whale sharks, big friendly giants of the ocean

Whale sharks are about the opposite of your archetypal shark. These gentle giants, the biggest fish in Earth’s oceans, are living on a steady diet of plankton (with the addition of small crustacean, fish and squids). There’s still a lot we don’t know about this wildlife marine species, though. Understanding…
Collared female with two cubs. (Credits A. Derocher)

24.07.2018 Animal tracking applications On the track of the polar bears

Polar bears live in a challenging environment for human beings, and getting close to them is not without dangers. Wildlife tracking using Argos PTTs has thus enabled us to know more about them. The polar bear (Ursus maritimus) is heavily dependent on sea ice, since they feed on seals (ringed…

23.07.2018 Animal tracking applications Two tags on a shark: a world first

The french association APECS (Association for the Study and Conservation of Selachians) is a Brest association dedicated to the study and conservation of sharks and rays. The members of this association regularly use Argos tags to be able to follow the selected specimens to better understand their behavior. Last…

19.07.2018 Animal tracking applications News about the Rana turtle

Do you remember Rana? This is the turtle collected and treated for four years by the Oceanographic Museum of Monaco. After his release and the few adventures to find the camera that filmed his first 24h of freedom, Rana has already traveled more than 300km. The Caouanne turtle…
Eurasian woodcock (credit Joseba Felix Tobar-Arbulu)

09.07.2018 Animal tracking applications Scolopax rusticola without frontiers

The Eurasian woodcock, Scolopax rusticola, is a very special bird as it is crepuscular. During the day, it rests in places where there is not much light.  Thus, this species was not very well known before the first tracking – in 2006, as before that the lightest Argos PPT was…

03.07.2018 Flash news The adventure of the turtle named Rana and her camera

Around the 21st of June, as part of an action led by the Oceanographic Museum of Monaco, Robert Calcagno, Damien Chevalier & Olivier Brunel released a sea turtle named Rana who had been receiving treatment for four years. To monitor its evolution an animal tracking system was set up…
An eel in the sea with a pop-up tag. Credits G. Simon, Perpignan University

27.06.2018 Animal tracking applications Eels become slightly less slippery thanks to Argos & goniometer

Eels are still nowadays a very mysterious fish species. To better know their swimming behaviour when leaving the European coasts, accelerometers are used in conjunction with Argos pop-up tags to estimate speed variations during vertical migrations and infer energy expense of eels leaving Europe to reproduce in the Sargasso Sea.
éléphant de mer avec une balise Argos (photo C. McMahon, IMOS/U. Sydney)

11.06.2018 Animal tracking applications Elephant seals diving for science

The marine animals living in the open ocean, and especially in the Southern Ocean, are among the ones which knowledge benefitted the most from Argos wildlife tracking. We discovered a lot about Southern Elephant seals, among those – depths of dive, paths followed, etc., all things completely unknown previously and…
Arctic fox (Credits A. Sokolov)

29.05.2018 Animal tracking applications Siberian Arctic fox on the move

Nowadays Arctic wildlife is often endangered by climate changes and human activities, and they are not always very well known. The arctic fox is a small animal, white in Winter, living around the Arctic circle. In Siberia it has been little studied for now, but miniaturization progresses make it possible…
Loggerhead turtle equipped with a satellite tag. Source: Miquel Gomila/SOCIB

15.05.2018 Animal tracking applications Tweeting Mediterranean Loggerhead turtles as oceanographers

Loggerhead turtle around Balearic Islands are equipped with Argos satellite tracking tags. Their data are used as oceanographic data source, and they also can be followed in real-time on Twitter, as a mean of raising awareness on the threats to this wildlife species and the way of helping protecting them.