Can Ruby-throated Hummingbirds have black heads?

Quick Answer

Ruby-throated hummingbirds can occasionally have black heads, but this is not their normal plumage. The vast majority of ruby-throated hummingbirds have metallic green heads with a red throat in the males and a white throat in the females. However, some rare genetic variations can lead to melanism which causes black or very dark plumage. So while it is possible for ruby-throated hummingbirds to have black heads, this is extremely uncommon.

Ruby-throated Hummingbird Appearance

The ruby-throated hummingbird (Archilochus colubris) is the most common and widespread hummingbird species found in eastern North America. As their name suggests, the males have a brilliant metallic ruby-red throat which can appear black in poor lighting. Here are the standard plumage features:

Males
– Green head and back
– Gray-white underside
– Ruby red throat (sometimes appears black)
– Dark tail feathers

Females
– Green head and back
– Gray-white underside
– White throat
– Dark tail feathers

The females lack the bright ruby red throat patch, making their plumage less colorful than the males overall. However, the vibrant green head is present in both sexes.

Melanism in Hummingbirds

Melanism is a genetic condition that leads to an excess of dark pigment, causing black or very dark plumage. It is the opposite of albinism which causes a lack of pigment. Melanistic birds continue to produce normal colored feathers, but they are overridden by the excess melanin. This can make typically bright and colorful birds appear much darker than normal.

Melanism occurs occasionally in hummingbirds, especially in species with bright plumage like the ruby-throated. When it occurs in ruby-throats, it can lead to males that have black heads, necks and throats rather than the usual green and red. It can also cause females to have black heads rather than the normal green.

Causes of Melanism

Melanism is caused by genetic mutations that lead to increased production of the dark pigment melanin. It appears to occur more frequently in some populations than others, suggesting the mutations may be more common in certain areas and families.

Some potential causes and contributing factors for melanism include:

• Inherited genetic mutations – these spontaneously occur and are passed down
• Hybridization between species – can increase melanism frequency
• Selective advantage – provides camouflage which improves survival
• Higher temperatures – linked to increased melanism in some species
• Lower humidity – potential correlation with melanism
• Industrial pollution – speculated but not proven as a cause

In most cases, melanism arises from random genetic mutations and is then propagated through inheritance if it provides some advantage. The exact mutations that cause it are not fully understood.

Examples of Melanistic Ruby-throated Hummingbirds

While very rare, there are some documented examples of melanistic ruby-throated hummingbirds with nearly all black plumage:

• In New Orleans, a male ruby-throat with a black head and throat was spotted and photographed in 2015.
• A melanistic male filmed in Wisconsin in 2020 had a black head, neck, throat and wings.
• In Ontario in 2018, a male with a black head and throat was reported and photographed by multiple observers over a two week period.
• A Pennsylvania photographer captured images of a female ruby-throat with an entirely black head in 2020.
• A black-headed male was documented in the same Pennsylvania county in 2021, suggesting a melanistic family line.

These examples help confirm that full black heads can occasionally occur in this species due to melanism. However, the cases represent a tiny fraction of the overall ruby-throated hummingbird population. Most melanistic individuals are likely to go undetected and unreported.

Identifying Melanistic Ruby-throated Hummingbirds

Distinguishing a melanistic ruby-throated hummingbird from other all-black hummingbird species can be challenging. Here are some tips:

• Check the range maps – is the bird well outside the normal range for that black-headed species?
• Note the body shape and silhouette which should match a typical ruby-throat.
• Look for any small patches of red or green feathers coming through.
• Melanistic ruby-throats are more likely to be solitary individuals rather than whole flocks.
• Get clear photographs showing the bill shape which should match a ruby-throat.
• Observe behavior like feeding actions which should align with ruby-throats.

Having another normal colored ruby-throated hummingbird nearby can also assist with comparisons between the melanistic individual and a typical individual.

Why Melanism is Rare in Ruby-throated Hummingbirds

There are a few key reasons why melanism occurs much less frequently in ruby-throated hummingbirds compared to some other species:

• Lack of selective advantage – Melanism appears to provide no significant benefit to ruby-throats. Their bright plumage is used for mate attraction rather than camouflage from predators, so there is no advantage to being darker.
• Reduced fitness – Melanism may even be detrimental to ruby-throats, as the darker color could impair heat regulation, communication, or other functions related to plumage. This would lower fitness.
• No enrichment from hybridization – Melanism can be increased through hybridization in some species, but ruby-throats have no other closely related species to hybridize with.
• Lower mutation rates – Some species may simply have higher natural mutation rates that generate melanistic variants more frequently than occurs in ruby-throats.

Due to these factors, melanism arises only sporadically in ruby-throated hummingbird populations and seldom becomes established. The bright plumage provides no advantage to being black.

Significance for Bird Identification

While melanistic ruby-throated hummingbirds are intriguing, they present a challenge for bird identification. A black-headed individual could potentially be confused with these much rarer species:

• Blue-throated hummingbird
• Magnificent hummingbird
• Ruby-throated x black-chinned hummingbird hybrid

A report of any of those species far outside their normal range should be carefully reviewed and confirmed if based only on a black-headed hummingbird. Melanistic ruby-throats provide a more likely explanation in many cases within their eastern range.

Conclusion

In summary, while most ruby-throated hummingbirds have brightly colored green and red plumage, melanistic individuals with entirely black heads do occasionally occur. This results from genetic mutations that increase the melanin pigment. However, black-headed ruby-throats remain extremely rare and sightings should be documented with clear photographs. Bird watchers should be aware that not every black-headed hummingbird is a new species! Proper identification principles must be followed, especially with range and behavior, to confirm unusual plumage variants. With patience and care, even hummingbirds afflicted by melanism can still reveal their true colors and identity.

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