Post, who believes that caribou may serve as an indicator species for climate changes including global warming, based his conclusions on data showing that the timing of peak food availability no longer corresponds to the timing of caribou births.
The study, which was conducted in collaboration with Mads Forchhammer at the University of Aarhus in Denmark, will be published in the 12 July 2008 issue of the Philosophical Transactions of the Royal Society of London.
Caribou -- which are closely related to wild reindeer -- are dependent on plants for all their energy and nutrients. Throughout the long Arctic winter, when there is no plant growth, they dig through snow to find lichens; however, in spring they rapidly switch to grazing on the new growth of willows, sedges, and flowering tundra herbs. As the birth season approaches, they are cued by increasing day length to migrate into areas where this newly-emergent food is plentiful.
But this routine, which has worked for millennia, is faltering because caribou are unable to keep pace with certain changes that have occurred as a result of global warming. When the animals arrive at their calving grounds now, pregnant females find that the plants on which they depend already have reached peak productivity and have begun to decline in nutritional value. According to Post, the plants -- which initiate growth in response to temperature, not day length -- are peaking dramatically earlier in response to rising temperatures. "Spring temperatures at our study site in West Greenland have risen by more than 4 degrees Celsius over the past few years," said Post. "As a result, the timing of plant growth has advanced, but calving has not."
The phenomenon, called trophic mismatch, is a predicted consequence of climate change, in which the availability of food shifts in response to warming, whereas the timing of demand for those resources does not keep pace. Trophic mismatches have been documented in birds -- with the most famous example being the study on Dutch birds and their caterpillar prey that was highlighted in former Vice President Al Gore's film An Inconvenient Truth -- but, until now, the phenomenon had not been observed in terrestrial mammals. "Our work is the first documentation of a developing trophic mismatch in a terrestrial mammal as a result of climatic warming," said Post. "And the rapidity with which this mismatch has developed is eye-opening, to say the least."
While Post and Forchhammer think it is possible that caribou will respond to a warming climate by advancing the timing of their reproduction, they are not convinced that the species will be able to compensate fully for the rapid rates of temperature change that are yet to come. "They're a little behind the game already and future warming will make it even harder for them to catch up," said Post. "This factor is just one of many related to climate change -- such as thaw-freeze cycles, ice-crust formation, and severe storms -- that may make it difficult for caribou populations to persist at their former abundance."
This research was funded by the University of Alaska, the Penn State Institutes of Energy and the Environment, and the National Geographic Society Committee for Research and Exploration.
Barbara K. Kennedy | EurekAlert!
Meadows beat out shrubs when it comes to storing carbon
23.11.2017 | Norwegian University of Science and Technology
Migrating Cells: Folds in the cell membrane supply material for necessary blebs
23.11.2017 | Westfälische Wilhelms-Universität Münster
High-precision measurement of the g-factor eleven times more precise than before / Results indicate a strong similarity between protons and antiprotons
The magnetic moment of an individual proton is inconceivably small, but can still be quantified. The basis for undertaking this measurement was laid over ten...
Heat from the friction of rocks caused by tidal forces could be the “engine” for the hydrothermal activity on Saturn's moon Enceladus. This presupposes that...
The WHO reports an estimated 429,000 malaria deaths each year. The disease mostly affects tropical and subtropical regions and in particular the African continent. The Fraunhofer Institute for Silicate Research ISC teamed up with the Fraunhofer Institute for Molecular Biology and Applied Ecology IME and the Institute of Tropical Medicine at the University of Tübingen for a new test method to detect malaria parasites in blood. The idea of the research project “NanoFRET” is to develop a highly sensitive and reliable rapid diagnostic test so that patient treatment can begin as early as possible.
Malaria is caused by parasites transmitted by mosquito bite. The most dangerous form of malaria is malaria tropica. Left untreated, it is fatal in most cases....
The formation of stars in distant galaxies is still largely unexplored. For the first time, astron-omers at the University of Geneva have now been able to closely observe a star system six billion light-years away. In doing so, they are confirming earlier simulations made by the University of Zurich. One special effect is made possible by the multiple reflections of images that run through the cosmos like a snake.
Today, astronomers have a pretty accurate idea of how stars were formed in the recent cosmic past. But do these laws also apply to older galaxies? For around a...
Just because someone is smart and well-motivated doesn't mean he or she can learn the visual skills needed to excel at tasks like matching fingerprints, interpreting medical X-rays, keeping track of aircraft on radar displays or forensic face matching.
That is the implication of a new study which shows for the first time that there is a broad range of differences in people's visual ability and that these...
15.11.2017 | Event News
15.11.2017 | Event News
30.10.2017 | Event News
24.11.2017 | Earth Sciences
24.11.2017 | Ecology, The Environment and Conservation
24.11.2017 | Earth Sciences