Food Webs: Arctic Ecology and Food Chains

Food Webs Charles Elton Bear Island Arctic Circle Bear Island Observations Very few species Food was scarce on land Food was plentiful in the sea  Was there a relationship between the food items? Observation Marine animals eaten by birds and seals Seabirds eaten by arctic f...

Food Webs Charles Elton Bear Island Arctic Circle Bear Island Observations Very few species Food was scarce on land Food was plentiful in the sea  Was there a relationship between the food items? Observation Marine animals eaten by birds and seals Seabirds eaten by arctic foxes Seals eaten by polar bears Relationships dubbed “food chains” More Complex than suspected Bird droppings contain nitrogen Nitrogen consumed by bacteria Bacteria used by plants Insects consume plants Birds and mammals start consumption Off to Nordaustland er Nordaustlander Less accessible Thick belts of ice made travel difficult Broken propellor Trip abandoned Stopped at Tromsø  The book that changed it all Lemmings? They don’t jump off cliffs!!! Thrown not Jumped Lemmings 50 pages on lemmings Massive swarms called “lemming years” Occurs periodically every 3-4 years Why the increase? Theories Weather fluctuations Lemmings have litters during the winter Long winter means more litters  Ersine Predation Zoologist assumed that animal populations were steady? Why the fluctuation? What was it affecting? Fur Trade reports Scoured for data on other species Fur trader records showed increases in arctic fox, lynx , and peregrines Food Chains Food is the currency of animal economies Basic class in animal society: plant eating herbivores Carnivores Carnivores “which has no enemies” Lower levels of food chain abundant English Oak example Numerous small herbivorous insects Some carnivorous insects A few warbler birds One or two hawks