Quick Answer
The Rufous Hummingbird is slightly larger than the Ruby-throated Hummingbird. The Rufous Hummingbird has an average length of 3.1-3.5 in and a wingspan of 4.3 in. The Ruby-throated Hummingbird has an average length of 2.8-3.5 in and a wingspan of 3.1-4.3 in. So while their sizes overlap, the Rufous tends to be a bit bigger on average.
Comparing Sizes
Hummingbirds are the smallest birds in the world, but there are differences in size between species. Here is a comparison of the Rufous and Ruby-throated Hummingbirds:
| Species | Length (in) | Wingspan (in) |
|---|---|---|
| Rufous Hummingbird | 3.1-3.5 | 4.3 |
| Ruby-throated Hummingbird | 2.8-3.5 | 3.1-4.3 |
As the table shows, the Rufous Hummingbird is slightly bigger than the Ruby-throated. The Rufous has an average length of 3.1-3.5 in compared to 2.8-3.5 in for the Ruby-throated. For wingspan, the Rufous averages 4.3 in while the Ruby-throated ranges from 3.1-4.3 in.
So while there is some overlap in their sizes, the Rufous is generally a bit larger than the Ruby-throated. The difference is small, but noticeable when comparing the two species directly.
Other Size Differences
In addition to the overall length and wingspan, there are some other size differences between Rufous and Ruby-throated Hummingbirds:
– Weight – The Rufous weighs 2.9-3.4 g on average while the Ruby-throated weighs 2.4-3.4 g. Again the Rufous is slightly heavier.
– Beak length – The Rufous has an average beak length of 0.65 in compared to 0.5 in for the Ruby-throated. The Rufous has a proportionally longer beak.
– Feet – The feet of the Rufous are slightly larger than the Ruby-throated’s. This matches their overall larger body size.
So in every dimension – length, wingspan, weight, beak, feet – the Rufous Hummingbird averages slightly bigger than the Ruby-throated. The differences may be small, but they are consistent.
Why the Size Difference?
What accounts for the Rufous Hummingbird being slightly larger than the Ruby-throated? There are a few possible reasons:
– Migration – The Rufous has one of the longest migration routes of any hummingbird, traveling between Alaska and Mexico. This extensive migration may have selected for a larger body size over time. The Ruby-throated migration is much shorter.
– Climate – The Rufous winters in colder climates than the Ruby-throated, reaching as far north as Alaska. Larger bodies can conserve heat better, which may give an advantage in colder climates.
– Nectar competition – In areas where Rufous and Ruby-throated Hummingbirds overlap, the larger Rufous may be better able to compete for nectar resources. Larger size could be beneficial when food sources are limited.
– Display features – Male Rufous Hummingbirds use plumage displays to attract females. A larger body can better support showy feathers and vigorous display flights. These mating displays may drive size evolution.
So in summary, the Rufous Hummingbird’s more extensive migration, expanded wintering range, competition for food sources, and courtship displays may all contribute to selective pressures resulting in its slightly larger size. The Ruby-throated has a much narrower range and migration which lacks these pressures.
Identification Tips
Because Rufous and Ruby-throated Hummingbirds are so similar in size, you can’t rely on size alone for identification. Here are some tips:
– Color – Male Rufous have an iridescent orange throat whereas Ruby-throated males have a bright red throat. Females are more difficult but Rufous has rusty sides and tail.
– Beak – The longer, slightly decurved beak of the Rufous is a good distinguishing mark from the shorter straight beak of the Ruby-throated.
– Tail – The broad, round-tipped tail of the Rufous differs from the narrow notched or forked tail of the Ruby-throat.
– Sound – The calls are very different, with the Rufous making a harsh buzzing sound and the Ruby-throated a series of high chirps.
– Range – Know the range and migration timing of each species. For example, if you see a hummingbird in midsummer in the Rocky Mountains, it’s almost certainly a Rufous.
So when trying to distinguish between these two hummingbirds, don’t rely only on size – look at colors, beak shape, tail characteristics, sounds, geographic range, and time of year. Proper identification requires looking at multiple factors beyond just size.
Conclusion
The Rufous Hummingbird is indeed slightly larger on average than the Ruby-throated Hummingbird. But the difference in length, wingspan, weight, and other physical dimensions is minimal. In fact their sizes overlap substantially. However, the consistency across all measures suggests there are likely evolutionary factors at play selecting for the Rufous’s larger size. So while you can’t rely on size alone to identify these species, the nuanced size differences reflect underlying environmental pressures and hummingbird ecology. Paying attention to the small details like size is part of fully appreciating the natural world.
