Why Niches Are Important
TREE SWALLOW
VS.
EASTERN BLUEBIRD
Niche Defined
• The functional role an organism plays in an ecosystem.
• It’s occupation.
• Herbivore, carnivore, omnivore, scavenger
• It’s relationships
• Predator, prey, partnerships with other organisms.
Niche Terms
• Competition A common demand by two or more organisms
upon a limited supply of a resource; for example, food,
water, light, space, mates, nesting sites. It may be
intraspecific or interspecific.
• Coevolution A specific role of a species within an ecosystem,
including its use of resources, and relationships with other
species.
• Mutualism A relationship between two species in which
both species benefit
• Predation An interaction in which one organism kills another
for food.
Niche Terms
• Predation An interaction in which one organism kills another
for food.
• Parasitism A relationship between two organisms of
different species where one benefits and the other is harmed
• Realized Niche The niche species actually occupies.
• Fundamental Niche The niche species could potentially
occupy.
Tree Swallow
Eastern Bluebird
Tree Swallow Niche
• Feeding Behavior
• Forages mostly in flight, often low over water or fields. May pick
items from surface of water while flying. Perches in bushes to eat
berries, and sometimes feeds on ground, especially in cold
weather.
• Diet
• Mostly insects, some berries. Diet is mostly insects, especially in
summer. Feeds on many flies, beetles, winged ants, and others.
Also eats some spiders, and will eat sand fleas (which are
crustaceans). Unlike our other swallows, eats much vegetable
material (up to 20% of annual diet, mostly eaten in winter).
Bayberries are main plant food, also eats other berries and seeds.
Eastern Bluebird Niche
• Feeding Behavior
• Does much foraging by perching low and fluttering down to
ground to catch insects, often hovering to pick up items rather
than landing. Also catches some insects in mid-air, and may take
some while hovering among foliage. Feeds on berries by perching
or making short hovering flights in trees.
• Diet
• Mostly insects and berries. Feeds on a wide variety of insects,
including crickets, grasshoppers, beetles, and many others; also
spiders, earthworms, snails, rarely small lizards or tree frogs. Also
eats many berries, especially in winter
Nesting Behavior
• Bluebirds won’t nest within 300ft. Of another bluebird.
• Tree swallows and bluebirds will nest next to each other even though
they both eat insects.
• Why?
NO
NO
YES!
Nesting Competition
• Bluebirds perch and drop on insects to feed.
• Swallows feed on flying insects.
• Bluebirds and swallows don’t compete for the same food.
• They occupy different niches!
0-30ft
300ft or more
100ft or more