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We are all part of an 'intricate' food chain

By SANDY FAIRFIELD February 7, 2013 · 4:24 PM
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THE CITRINE WAGTAIL is part of the great food chain of life. / Photos by Mik Yip

The expressions "it's a jungle out there," "dog eat dog" and "survival of the fittest" all refer to the hardships wildlife face to survive.

Each year, the Mountainaire Avian Rescue Society receives birds or animals that have been "snatched from the jaws of death."

All living creatures, including humans are part of a very intricate food chain in which each link depends on the others; a collapse at any level can destroy the chain. If we all ate the same food it would not take long before all the available food would be consumed, so species have diversified and become specialists.

Species can be categorized according to their food preferences.

There are five main food groups — carnivores, herbivores, omnivores, insectivores and frugivores. Species are equipped with specially adapted features such as beaks, feet, mouths, and teeth  to access and consume the food.

• Carnivores, including raptors, seals and lions, eat flesh, which they catch and consume using sharp teeth, beaks or talons.

• Herbivores eat a variety of plants, flowers nectar or other vegetation; species include cows, deer, and swans.

• Insectivores consume a huge number of insects, their eggs and larvae, which in turn keep the bug population under control; they also keep trees and plants healthy by gleaning insects from leaves, bark and buds. Many bird species are invaluable in this department including bats, swallows, nuthatches and chickadees.

• Frugivores are often overlooked but are essential seed dispersers, ensuring that plants and trees continue to thrive. Orangutans, fruit bats and monkey owls are examples of species that eat the fruit and then travel many miles before ridding themselves of the seeds.

• Omnivores, also known as the "cleanup crew," are often opportunistic feeders, (humans are in this group) eating a huge variety of foods. Omnivore bird species include crows, ravens and vultures.

By understanding this complex chain of specialized species and their food preferences, we can better understand why sometimes their feeding habits offend us.

Some birds are very specific with their choice of meat, some eagles almost exclusively dine on fish, others have a preference for deer or seal meat, whilst others supplement their diet in harsh winters with ducks, or other water fowl.

It is not unusual if food is in short supply for a hawk to prey upon an errant chicken that strays from the coop, it naturally preys on other birds. Owls are another species that prefer a diet of rodents but it is normal for larger owls such as great horned, snowy, and barred owls to prey upon the smaller saw whet and pygmy owls.

Many species protect themselves from becoming prey by their choice of food and the time when they hunt. This way, they eat different things and avoid their predators.

Although it is often difficult for us to witness a raptor catch and devour its prey, we have to remember this is natural behaviour. I think we would be less than elegant if we attempted to hold our food in our feet and eat with just our mouths!

We would ask that anyone who witnesses this normal feeding process to leave the birds to their fate. The predator will act more quickly and the prey will not suffer, it is almost certain a discarded meal that will not survive the initial attack.

We must also remember that raptors provide a valuable service by culling the sick or weak birds; they take those birds that do not react normally to the presence of the raptor. Many hawks also prey upon pigeons and starlings.

Both of these birds are invasive species, which are competing for food with our native species. Our wildlife policies do not allow us to rehabilitate or release these species should they be found injured.

Many small birds that gather in large flocks at the back yard feeders are particularly vulnerable to attack but in fact this helps keep their populations healthy. Enjoy your bird-watching and if you should witness a raptor feeding, look upon this as a positive experience and leave the bird to enjoy its meal.

Remember, wildlife is protected by laws. Please make sure you do not wrongly identify a bird that is catching another bird species, beaks and feet will tell the tale, slender short beaks cannot eat flesh they are insectivores.

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To report injured wildlife, call our toll free number 1-800-304-9968, for any other information call 250-337-2021, or visit www.wingtips.org.

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MARS will hold its annual Eagle Fest on Feb. 23 at the Maritime Heritage Centre in Campbell River. There will be guest speakers and live ambassador birds, including a bald eagle; it is always a fun and interesting day.

Sandy Fairfield is the educational co-ordinator for the Mountainaire Avian Rescue Society (MARS). The MARS column appears every second Friday.