The Calliope hummingbird (Selasphorus calliope) is the smallest bird species in North America and has unique dietary requirements to sustain its high metabolism and energy needs for flight. In this article, we will explore what these tiny birds eat and how their diet supports their energetic lifestyle.
Nectar is their main food source
Like all hummingbirds, the Calliope hummingbird gets most of its calories from drinking nectar from flowers. Their long, slender beaks and tongues are specially adapted to reach into flowers and lap up the sugary nectar.
Flowers utilize nectar to attract pollinators like hummingbirds. The nectar provides a high-energy food source to fuel the hummingbird’s metabolically demanding hovering flight. Gram for gram, nectar has more calories than sugars like sucrose or high fructose corn syrup.
Some favorite nectar sources for Calliope hummingbirds include:
- Coral bells
- Columbines
- Penstemons
- Paintbrushes
- Salvias
- Trumpet vines
- Red-hot pokers
- Firecracker flowers
In one day, a Calliope hummingbird may visit 1,000 or more flowers. They have excellent memory and will repeatedly return to plentiful and reliable nectar sources.
Sugar concentrations preferred
It was once thought hummingbirds preferred higher sugar concentrations, akin to drinking soft drinks. However, research shows Calliope hummingbirds gain the most weight when feeding on nectars with moderate sugar concentrations of around 20-25%.
Nectars with lower concentrations may not provide enough calories, while excessively sweet nectars may overwhelm their digestive system. Flowers utilize a range of sugar concentrations in their nectars, and hummingbirds can discriminate between them.
Calliope hummingbirds will reject artificial nectars outside of their optimal range. This may be why they often ignore backyard hummingbird feeders with sugar water more concentrated than 25%.
Insects provide protein
While nectar provides calories, Calliope hummingbirds also consume insects and spiders to meet their protein requirements.
They capture insects on the wing or pick them off vegetation. Preferred insects include:
- Mosquitoes
- Fruit flies
- Gnats
- Aphids
- Small bees
- Spiders
Consuming more insects provides greater nutrition fornesting and fledgling hummingbirds with high protein demands.
Water intake
Like all animals, Calliope hummingbirds require water to avoid dehydration. They get much of their water needs from the nectar they drink. If excessively dehydrated, they may sip water from streams, sprinklers or bird baths.
How do Calliopes feed?
Here’s a quick overview of how Calliope hummingbirds eat:
- Drink nectar – Lap up sugar-rich nectar from flowers using a long tongue.
- Capture insects – Forage on the wing snatching tiny insects.
- Perch and feed – Occasionally perch to consume larger captured insects.
- Lick water – Lick droplets of water if dehydrated.
Their feeding habits support hovering flight to approach thousands of scattered flowers and prey.
High metabolism
Hummingbirds have incredibly fast metabolisms to power Muscles for hovering flight. Their hearts beat up to 1,200 times per minute and they breathe up to 250 times per minute even at rest.
To meet these high energy demands, Calliope hummingbirds eat frequently throughout the day. Their intake is estimated at half to three-quarters of their total body weight in nectar each day.
Adequate food availability is critical, as they will starve rapidly if deprived of food for more than a few hours.
Role as pollinators
By drinking nectar, Calliope hummingbirds serve as important pollinators. As they move from flower to flower, pollen sticks to their head and beaks and is transferred to other blooms.
Their ability to hover precisely enables them to reach into a diversity of uniquely shaped flowers adapted for hummingbird pollination. Their preferencs for red tubular flowers perfectly matches many pollinator-dependent species.
This crucial ecological role means some plants depend entirely on Calliope hummingbirds for pollination and seed production.
Adapting to flower availability
Different flowers come into bloom at varying elevations as seasons progress. Calliope hummingbirds adapt by going on migratory journeys tracking these “nectar corridors” of blooming flowers.
In spring, they follow lower elevation flowers up mountainsides as snow melts. In late summer, they migrate back down chasing the flowering season.
Backyard bird feeders can support migrating and breeding Calliopes when fewer flowers are available. They remember locations of reliable food sources from year to year.
Torpor use to conserve energy
To survive periods of cold weather or inadequate food, Calliope hummingbirds can enter torpor. This low-energy state is like hibernation and lowers their metabolism by 50-95%.
Their body temperature drops from 104F to 50-60F. Heart and breathing rates slow dramatically. Theycan arouse from torpor within an hour by detecting food.
Coping with cold temperatures
Calliope hummingbirds are well-adapted to deal with cold temperatures while breeding at high elevations or during migration. Strategies include:
- Hypothermic nighttime roosting – Lower body temperature by 15-20F at night to conserve energy.
- Pluming – Fluff out breast feathers to trap more insulating air.
- Shivering – Rapidly contract flight muscles to generate heat.
- Wind barriers – Take shelter from the wind behind trees or vegetation.
Despite their small size, they can slow heat loss enough to cope with freezing temperatures. Access to adequate food stores provides the energy to keep their metabolism running high to generate heat.
Interesting feeding behaviors
Some interesting discoveries about Calliope hummingbird feeding include:
- Bee balm nectar theft – They will pierce the base of bee balm flowers to rob nectar, avoiding pollination.
- Nectar guarding – Males guard clumps of flowers to feed exclusively and chase away rivals.
- Flower preference learning – Chicks likely imprint on local flower foods from their mothers.
- Reliance on red flowers – They ignored introduced flower species lacking red hues.
Researchers continue making new discoveries about the nuances of hummingbird foraging ecology and behavior.
Drinking from feeders
Convenient artificial nectar sources are readily accepted by Calliope hummingbirds in the form of backyard feeders. Feeders provide vital nutrition during migration or when flowering is reduced.
Calliope hummingbirds can be attracted to feeders using these strategies:
- Fill with 20-25% sugar nectar – Higher concentrations may be avoided.
- Use red feeders – They are attracted to red colors.
- Position near flowers – Place feeders amid natural food sources.
- Avoid bees – Use bee-proof feeder ports.
- Refill often – Fresher nectar is preferred.
With over-wintering populations expanding, maintaining year-round feeders can support Calliope hummingbirds that linger longer on their breeding grounds.
Impact of habitat loss
The availability of food-rich habitats affects the distribution, migration timing, and health of Calliope hummingbird populations. Habitat loss can impact them through:
- Fewer wildflowers – Reduces nectar food supplies.
- Fewer insects – Less protein for growth and reproduction.
- Burned forests – Destroys nesting sites and food sources.
- Climate shifts – Alters timing of blooming flowers and insect populations.
Promoting flower meadows, native plants, and healthy forests can counteract these habitat pressures to support Calliope hummingbirds.
Unusual food supplementation
In extreme conditions lacking adequate flowers or insects, Calliope hummingbirds may resort to unusual alternative food sources such as:
- Tree sap – Provides sugars, but malnutrition risk from lack of nutrients.
- Insect guts – Extract partially digested nutrients from discarded insect prey.
- Aphid honeydew – Sugary secretions from sap-sucking insects.
- Pollen – Minimal nutrition and may cause digestive issues.
These inferior food sources are not sustainable nutrition strategies, so access to flowers and insects is essential.
Nectar robbing
Sometimes Calliope hummingbirds will exhibit “nectar robbing” when flower supplies are low. This means they steal nectar by piercing a hole at the flower’s base rather than pollinating via the opening.
Strategies used may include:
- Cling sideways – Access base of vertical flower.
- Poke beak tip in – Pry open seam to enlarge hole.
- Lick up nectar – Lap out nectar from base reservoir.
- Move rapidly – Quickly steal from multiple flowers.
This behavior reduces their pollination contributions. But it efficiently obtains concentrated nectar when needed.
Eating at feeders
Calliope hummingbirds exhibit some interesting behaviors while eating at backyard feeders, including:
- Guarding feeders – Males chase other birds from feeders.
- Energy maximizing – Consume higher volumes when sugar content drops.
- Feeding upside-down – Unique ability to feed upside-down from inverted feeders.
- Tongue flicking – Flick tongues in and out 13 times per second.
- Perch feeding – Occasionally perch to drink longer.
Research shows they can learn to associate the colors and locations of feeders with nectar rewards to optimize feeding.
Diet composition
The typical diet composition of Calliope hummingbirds consists of:
- 60-80% sucrose nectar
- 20-40% insects like gnats, aphids, spiders
- Water, tree sap, and other sugars opportunistically
The proportions vary across life stages and seasons. For example, females boost insect protein prior to nesting and fledglings need more insects for growth.
Energy requirements
The tiny Calliope hummingbird has surprising energy demands. Just to survive overnight, they burn up to 1/3 of their stored calories.
Their estimated daily energy requirements are approximately:
- idle – 12.6 kcal
- active – 17.5 kcal
- breeding male – 30 kcal
These high metabolism birds must eat constantly day and night to meet energy needs. Their extreme energy expenditure illustrates the sustained effort required for them to live at the edge of existence.
Daily food requirements
The miniscule Calliope hummingbird requires relatively large amounts of food daily. For example, an active 4 gram adult may consume:
- Nectar – 0.6-0.9 grams of sugar (~20% of body weight)
- Insects – 100-200 individual insects
Nestlings are estimated to consume over half their body weight in insects at each feeding by the mother. Food demands are extensive for their tiny bodies.
Survival adaptations
Multiple adaptations help Calliope hummingbirds survive on limited and variable food supplies:
- Speed – Fly up to 50 mph to rapidly reach scattered flowers.
- Maneuverability – Hover and fly backwards to access all flower angles.
- Color vision – See colorful red tubular flowers preferred for nectar.
- Flexible wings – Beat wings up to 80 times per second.
- Forked tongue – Doubled tongue tips lap nectar efficiently.
These specializations allow Calliope hummingbirds to exploit scattered, ephemeral food sources across diverse landscapes.
Conclusions
In conclusion, Calliope hummingbirds have unique dietary adaptations to their high-energy lifestyle:
- They primarily consume flower nectar and insects.
- Their diet supports hovering flight and fasting periods.
- They have a specialized tongue and bill for nectar feeding.
- They follow blooming flowers across seasons and altitudes.
- Backyard feeders provide critical food support.
- Conserving flower-rich habitats ensures adequate food supplies.
The Calliope hummingbird survives at the limits of size and energy constraints. Their specialized feeding behaviors provide key insights into their delicate yet remarkable existence.
