Apex predators have big effects on the animals and plants lower down the food chain. If they become extinct in an area, many changes happen. In recent times, it is often humans who have removed top predators.
An example of apex predators affecting an ecosystem is in Yellowstone National Park. After the gray wolf was reintroduced, in 1995, researchers noticed big changes occurring in the Greater Yellowstone Ecosystem. Elk, the primary prey of the gray wolf, became less abundant and changed their behavior. This freed the riparian (river) zones from constant grazing. This allowed willows, aspens, and cottonwoods to grow, so creating a habitat for beaver, moose, and scores of other species. In addition to the effects on prey species, the gray wolf's presence also affected the park's grizzly bear, a vulnerable species. The bears, emerging from hibernation, chose to scavenge off wolf kills after fasting for months. They can also eat wolf kills in autumn to prepare for hibernation. As grizzly bears give birth during hibernation, a greater food supply may improve the mother’s nutrition and increase the number of cubs. Dozens of other species, including eagles, ravens, magpies, coyotes, and black bears, have been seen scavenging from wolf kills.
References[change | change source]
- Egan, Logan Zane; Téllez, Jesús Javier (2005). "Effects of preferential primary consumer fishing on lower trophic level herbivores in the Line Islands" (PDF). Stanford at Sea. Stanford University. Retrieved 2010-01-25.
- Pace, M.L.; Cole J.J.; et al (1999). "Trophic cascades revealed in diverse ecosystems". Trends in Ecology and Evolution 14 (12): 483–488. doi:10.1016/S0169-5347(99)01723-1. PMID 10542455.
- Lister, B. & McDaniel CN. "The wolves of Yellowstone" (PDF). 2006-04-17. pg. 2. Retrieved 2010-01-25.
- Wilmers, Christopher C. (2004). "The gray wolf – scavenger complex in Yellowstone National Park" (PDF). p. 56. Retrieved 2010-01-25.
- Levy, Sharon (2002). "Top dogs". Retrieved 2010-01-25.
- Wilmers, Christopher C. (2004). "The gray wolf – scavenger complex in Yellowstone National Park" (PDF). p. 90. Retrieved 2010-01-25.
- Robbins, Jim (1998). "Weaving a new web: wolves change an ecosystem". Smithsonian Zoogoer (Smithsonian Institution) 27 (3). Archived from the original on 10 February 2010. https://web.archive.org/web/20100210224148/http://nationalzoo.si.edu/Publications/ZooGoer/1998/3/weavingwolfweb.cfm. Retrieved 2010-01-25.
- Wilmers, Christopher C.; Getz, Wayne M. 2005. "Gray wolves as climate change buffers in Yellowstone". PLoS Biology 3 (4): e92. . Retrieved 2010-01-25.