|Fragments in the Amazon, Photo from Google Earth|
Ideally, if we wanted to save a species, we would conserve as much of that species' habitat as possible. It's a no brainer. The reality is often different. Continuous stretches of rainforest would be wonderful, but sometimes only parts of an area can be protected. Maybe the government decides that a highway is crucial to connect an outlying town to nearby cities and a forest is interrupted and cut in two pieces. Or maybe parts of a savanna are sold off as farmland, disrupting continuous forests and instead making patches of forest. Either way, the landscape changes and life has to cope.
Dispersal of plants and animals is challenging when that plant or animal has to cross a stretch of non-habitat. A bird can cover that highway or palm oil plantation by flight, but a howler monkey or a sloth is going to have a much harder time crossing that space, missing breeding opportunities, foraging opportunities, dispersal opportunities and unable to move into new habitat if needed.
A troop of monkeys may survive just fine in parcel X of forest, but imagine there's a drought. They're starving, visibly losing body weight, mothers losing infants, and they need to feed from a patch of trees that they wouldn't normally eat from because the leaves provide such low nutrition but now they have no choice. Let's say that patch of typically undesirable trees in what is now parcel Y. Parcel Y is separated from the monkey's forest by a rice field. Can our troop of staving monkeys cross the rice field safely to get to that much needed resource? A juvenile jaguar reaches sexual maturity and needs to find a mate so that he can breed and increase his fitness, or the number of offspring an individual produces that survive to sexual maturity. The only available mates in this jaguar's forest are close relatives. If the jaguar breeds with a close relative, inbreeding may become a problem. Inbreeding over time decreases the genetic diversity of a species, making the species more susceptible to disease and genetic defects. These are just two examples of animals that do better with continuous habitat or with patches of habitat that they can cross. If that jaguar can't cross into another patch of forest to mate with a non-relative, he may never produce any offspring. If those monkeys can't cross the rice field, their population numbers will likely decrease even further and the troop won't be around for very long.
|This bridge allows wildlife to safely cross above the highway|
Wildlife corridors are created to solve these problems. Corridors may be designed specifically with a particular species in mind or more broadly to conserve multiple species. They may be reconstructed to look like the two habitats they're connecting or they may be more artificial. The Jaguar Corridor Initiative seeks to use farmland and other human modified areas as corridors where, while humans may use and own these lands, the jaguars can cross safely. Wildlife corridors allow species to move between fragments that they otherwise may struggle or fail to reach and they are proven to increase plant biodiversity. They're monitored to better understand if those corridors are actually being used. To check out more about the latest in corridor science, be sure to visit Conservation Corridor.
Food for thought: what might be some of the challenges or barriers be to creating these wildlife corridors?
True or false: an animal or plant only has to cope with a patchy habitat if humans have been involved.
Answer: false. Patches are created by rivers, by mountains and in other natural ways. Patches of habitat are not always man-made.