Bald eagles diet :Sea otters are known as a keystone species, filling an important niche in marine communities without them, entire ecosystems can collapse. Scientists have found, however, that sea otters may even have effects that extend to terrestrial communities and alter the behavior of another larger predator: the bald eagle.
Communities in coastal marine environments bald eagles diet, turn algae can reach a height of 250 meters and harvest trees in a forest, providing food, shelter and protection for fish and invertebrates. The most important bald eagles diet of these giant algae enemies are little urchins, a few centimeters in diameter, which live in the kelp spikes and eat its tissues. When urchin populations become too large, they can defoliate entire kelp forests, leaving only barren remains.
Enter the sea otter otters can eat bald eagles diet the hedgehog on the edge all, making it the largest predator hedgehog. The presence of the otter "kept urchin populations in check and maintains the balance of the ecosystem.
Scientists have known about these interactions bald eagles diet kelp forest community since 1970. But in the October issue of the journal Ecology, Robert Anthony and colleagues report that the presence or absence of otters can also affect the speed of bald eagles, a predator of the neighboring land.
Anthony is an ecologist with the Cooperative bald eagles diet Research Unit at Oregon Fish and Wildlife Service U.S. Geological Survey and Oregon State University.
Bald eagles live in high densities along bald eagles diet the Aleutian Islands, off the coast of Alaska and place their nests on islands, coastal cliffs and coastal batteries sea Historically, more than 90 percent of the food from the ocean eagles. Sea otters once also held a wide variety of coastal marine environments near these islands, but in recent years, otter populations have declined in response to their main predator bald eagles diet.
"Everything indicates that a greater number of killer whales as the direct cause of the sea otter decline in southwest Alaska," says co-author Jim Estes of the USG and the University of California Santa Cruz. "Otter decline bald eagles diet has resulted in a change in the phase of a phase state dominated by algae in a state of deforested stage coastal ecosystem."
This change means that bald eagles diet far fewer eagles kelp forest area fishermen. In response, the Eagles have adjusted their foraging tactics. Anthony and his colleagues examined the remains of prey bald eagle nests in 1993 and 1994, when otters were abundant and kelp forests were healthy and, in 2000, 2001 and 2002, when bald eagles diet otters are rare and seaweed forests had collapsed.
They found that when otters were abundant bald eagles diet, eagle prey consisted mainly of fish and kelp forest otter small Sea. When otters are rare, however, the proportion of seabirds in the diet of eagles was much higher.
Anthony explains that because the eagles defend territories in dense patches along the coast and there are few terrestrial animals to eat, they need to be flexible in what they hunt bald eagles diet.
"These bald eagles are opportunistic hunters bald eagles diet, because of their evolutionary history," he said. "They have developed the power to defend territories against members of the same species along the coast and the terrestrial environment provides very little for them. So feeding in the open sea. "
Anthony and his colleagues also found that the eagles were aged on average during the period 2000-2002, bald eagles diet Anthony think this could be the result of a diet rich in calories in seabirds increasingly dominated by Eagles .
"In all of the species, their diet can be quite varied, but here it seems that the regime change had a neutral or positive effect bald eagles diet," he said. The propensity of the eagles to adapt quickly to a changing environment may be allowed to flourish, but Anthony also cautions that adapting to this scenario might be difficult for the specialized predators bald eagles diet.
The results are the first to demonstrate that the presence or absence of otters influences a terrestrial animal, and that links the complex food chain can be up to five different levels of the food chain of the sea otter sea urchin seaweed, marine fish and finally bald eagles.
"Descendants of can bald eagles diet be very far from their origin," said Anthony. "Effects of large predators can affect the entire ecosystem in ways that we are only beginning to understand."
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