Grizzly bears are generalists that eat lots of different stuff, consuming various blends of plant and animal protein depending on where they live. The relative abundance of high quality food can have a big effect on bears. Kodiaks, a subspecies of grizzly, are huge because they populate an island in Alaska with enormous quantities of fish to eat. On the other hand, interior grizzlies like the ones in the Canadian Rocky Mountains are predominantly herbivorous because there are not as many fish to eat this far from the ocean. As a result, these bears are much smaller and reproduce at a much slower rate than coastal bears. With less availability to high-protein foods, these interior populations have to put more time into eating and are more susceptible to stress from human disturbance.
Find out more about grizzly bear diet.
Not so long ago, before the pioneers headed across the continent, grizzlies lived all over western North America, in forests, across the grassland plains, even in Mexico. As land was settled for cities and agriculture, grizzlies were forced from these areas. At one time it was estimated that more than six thousand grizzlies lived in the Province of Alberta, but now there are less than seven hundred. Currently, there are only about a thousand grizzlies living in the continental United States.
This map shows the dramatic shift in grizzly bear range over the past 150 years.
Phenology is the study of how seasons and inter-annual variations in climate affect the life cycles of plants and animals. This includes things like fish spawning in autumn, wildebeests migrating during the rainy season, or when flowers bloom in spring. Grizzly bears maximize their nutritional intake by exploiting the different times that plants, animals, and insects are available throughout their habitat. A big focus of phenology is observing the time when spring begins, as it has been slowly beginning earlier over the past century due to climate change. As a result, the bear’s ingrained feeding-schedule may not match the altered life-cycles of the things they eat, which is detrimental to their survival. This misalignment of schedules between species that rely on each other (or get eaten by each other) is called trophic mismatch. Another example includes flowers blooming earlier because of warming global climate, where plants have finished flowering before their insect pollenators have had a chance to even hatch – This can impact an entire ecosystem.
Watch this TED-Ed Lesson to learn more about phenology and the hazards of trophic mismatch.
Satellite Remote Sensing
I bet you know more about satellite Imagery than you think, and you probably use it on a daily basis. Google Earth is a mosaic of satellite and areal imagery weaved together to make a seamless interface that you can use to navigate a city, look at your house, or plan a hike. Despite what you see in the movies, satellites can only zoom in to a pixel-resolution of about 50-60cm, they can’t identify people, or read newspapers, but it’s still pretty impressive considering that they’re orbiting 700km away. Taking pictures by satellite is called remote sensing, which essentially means ‘collecting information from a distance’. These sensors are way more sensitive than our eyes and are able to detect the invisible ultra-violet and infra-red sections of the light spectrum. This allows researchers to find things in an image that they couldn’t normally see. For instance, plants absorb a lot of red light to use for photosynthesis, and reflect a lot of green light that they don’t need, that’s why they look green to us. However, plants reflect about four times more infra-red light than green light which makes them much easier to detect using these specialized sensors.
Watch this video to learn more about how remote sensing is used to study our planet.