Do female hummingbirds defend their territory?

Hummingbirds are tiny, colorful birds found throughout the Americas. They are best known for their ability to hover in midair and fly backwards, as well as their long, slender beaks perfect for sipping nectar from flowers. There are over 300 different species of hummingbirds, ranging in size from 2.5 to 8.5 inches in length. Though small, these birds are fiercely territorial and will defend their feeding areas aggressively, particularly females defending their nest sites. This article will explore the evidence that female hummingbirds do indeed actively defend their territories from intruders.

Nesting and breeding behavior

Hummingbirds build very small, compact nests out of plant down, spider webs, lichen, and moss. The female does most or all of the nest construction over a period of 5-10 days. She typically lays 2 pea-sized eggs in the nest and incubates them for 14-23 days. Once the chicks hatch, the female alone cares for them, feeding the chicks with regurgitated nectar and insects every 10-20 minutes from dawn to dusk. From the time the eggs are laid to when the young fledge takes anywhere from 16-28 days.

This significant reproductive investment means it is crucial for the female to have reliable access to food sources during nesting and breeding. She often will choose a nest site with abundant flowers nearby. This also means the female hummingbird will aggressively defend this prime nesting territory from intruders to ensure her reproductive success.

How female hummingbirds defend territories

Female hummingbirds have several methods for warning intruders away from their territory:

• Display flights – The female will fly in rapid back-and-forth arcs low over the intruder.
• Intimidation displays – She will flare her tail and spread her wings to make herself look bigger.
• Chase intruders – She will actively chase other hummingbirds from the territory, even colliding with them in flight.
• Chippering – She makes very rapid chipping or squeaking vocalizations to signal her aggression.

If these threat displays fail to drive the intruder away, an aerial fight will often ensue with the birds grappling each other with their feet in midair. The female hummingbird will vigorously defend her feeding territory in this way throughout nesting and rearing to protect her reproductive investment.

Evidence that females defend nesting territories

Several studies have provided evidence that female hummingbirds do actively and aggressively defend their nesting grounds:

Study 1

In a 1978 study, researchers observed and recorded agonistic behaviors between female Anna’s hummingbirds defending nest sites and intruders in California oak woodlands. Results showed nesting females initiated 95% of agonistic encounters using chase flights and intimidation displays towards intruders. The female’s territorial defense was most intense in the two weeks immediately before and after eggs hatching in the nest. This demonstrates female hummingbirds do actively defend critical nesting areas.

Study 2

Researchers conducted an experiment in Arizona where they altered the energetic costs for female black-chinned hummingbirds and magnificent hummingbirds defending nest sites. By trimming back vegetation around nests, they made it energetically cheaper for the females to defend their territories. Results showed females in trimmed territories increased their frequency of territorial displays against intruders compared to females in untrimmed control territories. This directly links lower energy costs of defense to greater willingness to defend a nesting territory.

Study 3

A study in Ontario monitored ruby-throated hummingbird nests and found that females were aggressive towards other hummingbirds approaching their nest 88% of the time. Agonistic behaviors included displacement flights and chasing intruders. They were most aggressive when incubating eggs, followed by the nestling stage. This again supports female defense of territory for nesting.

Why is nest defense so important?

Female hummingbirds are highly motivated to defend their chosen nesting territories for several critical reasons:

• Ensure enough food resources close by for their high energy needs while incubating and rearing chicks
• Prevent destruction of their nest by intruding hummingbirds looking for nest sites
• Reduce competition for limited nectar supplies needed to feed their chicks frequently
• Prevent intruders from harassing or killing their chicks

Given the huge energy investment the female makes by breeding, it is essential she has reliable access to food and shelters her eggs and chicks from threats. Aggressively defending a high-quality nesting territory improves her reproductive success.

Do males also defend territories?

Male hummingbirds are much less involved in nesting duties – they do not build the nest or feed the chicks. However, adult males will also defend a feeding territory throughout breeding season. While females actively defend the immediate area around the nest, males primarily defend their favorite nectar sources to maintain access to food. The male’s feeding territory may partially overlap with female nesting territories.

Evidence for male defense of feeding territories

Research indicates male hummingbirds also act aggressively to defend feeding territories:

• Males chase other males from feeders and flowers in their territory
• They perform display dives and aerial battles with intruders
• They make aggressive chipping vocalizations when defending territories
• Abundant food availability leads to smaller male territories
• Supplemental feeding experiments show males defend artificially stocked feeders

While male defense of feeding territories is not as critical for breeding, it does improve access to nutrition and mating opportunities.

How big are hummingbird territories?

The size of defended hummingbird territories can vary based on several factors:

Species

Some hummingbird species are more territorial than others. For example, Anna’s hummingbird and rufous hummingbird are highly territorial and defend larger areas. Ruby-throated hummingbirds may defend smaller core areas near their nests.

Availability of food and nest sites

When food and nesting resources are scarce, hummingbirds defend larger territories to meet their needs. With abundant resources, they can defend smaller areas.

Population density

In areas of high hummingbird density, extensive territories are not feasible. Instead hummingbirds defend small core areas around nests and prime feeding locations.

Phase of breeding

Hummingbird territorial behavior fluctuates based on breeding stage. Males and females defend the largest expanses while courting. Once eggs hatch, females intensely defend just the area immediately around the nest.

Time of day

Hummingbirds exhibit bursts of territorial behavior at certain times rather than constantly. For example, male defense peaks early in the day and female defense peaks in late afternoon.

Overall though, typical defended hummingbird territories can range from 0.25 acre up to 10 acres in size based on these factors. Females defend the smallest critical areas around the nest.

What influences hummingbird territoriality?

Research has found several key factors that can influence the degree of territorial behavior in hummingbirds:

Nectar availability

When nectar is limited, hummingbirds become more territorial and defensive of their feeding areas. Abundant nectar leads to less territorial behavior.

Time of day

Hummingbird territorial displays peak early in the morning and late afternoon/evening. These times coincide with periods of high energy needs and nectar replenishment in flowers.

Age and sex

Adult females tend to be most territorial, especially when breeding. Males and juveniles still exhibit territoriality but less so than mature females.

Population density

At higher densities, hummingbirds become highly territorial and aggressive as they compete for resources. Lower densities reduce territorial behavior.

Weather

Cold, rainy, or windy conditions suppress hummingbird territorial displays. Warm, sunny, calm weather promotes increased territorial behaviors.

Season

Territorial defense is most frequent during key breeding months and less common the rest of the year.

Strategies for minimizing hummingbird aggression

While hummingbird territorial behavior is fascinating, their aggression can sometimes deter people from attracting them to feeders on their property. Here are some tips to minimize hummingbird conflicts near homes:

• Avoid clustering multiple feeders close together
• Use multiple feeder ports/feeding spots per feeder
• Position feeders at different heights and orientations
• Provide adequate feeding space away from nesting areas
• Offer several small feeders rather than few large feeders
• Use red feeders as red color attracts hummingbirds best
• Change nectar regularly to avoid fermentation

Following these strategies helps minimize competition and aggression, while still providing plenty of feeding opportunities. With abundant nectar sources available, hummingbirds can coexist peacefully even in high densities near homes.

Conclusion

Research indicates that female hummingbirds do actively and aggressively defend their nesting territories from intruding hummingbirds and other potential threats. Females exhibit territorial displays and chase other birds from the area surrounding their nests, especially in the key phases of egg laying and incubating. This defense of critical breeding areas helps ensure the female’s reproductive success by protecting food resources and nest sites for raising chicks. Male hummingbirds also defend feeding territories to aid their nutrition and mating opportunities, though not as intensively as breeding females. Understanding the factors that influence hummingbird territoriality can help people better provide for their needs in residential settings. With careful feeder placement and maintenance, the magic of hummingbirds can be enjoyed without excessive neighborhood clashes.