Black swifts are a unique species of bird found primarily in western North America. Their size and dimensions are often a point of curiosity for bird watchers and ornithologists. In this article, we will explore several key questions related to the size of black swifts:
How long do black swifts grow?
Black swifts range in total length from about 4.7 to 5.5 inches (12 to 14 centimeters). Their wingspans range from about 12.2 to 13.8 inches (31 to 35 cm). This makes them slightly smaller in length and wingspan compared to their relative the chimney swift.
How much do black swifts weigh?
Black swifts weigh very little, with a weight range of just 17 to 30 grams. This light body weight allows them to stay aloft for incredibly long periods of time. In fact, black swifts are known to sometimes remain continuously airborne for periods of 200 days or longer!
How do the sizes of male and female black swifts compare?
There is very little size difference between male and female black swifts. Females tend to be slightly heavier, but only by a few grams on average. The wingspans and lengths of males and females largely overlap as well.
| Measurement | Male Size Range | Female Size Range |
|---|---|---|
| Length | 4.7 – 5.5 in (12 – 14 cm) | 4.7 – 5.5 in (12 – 14 cm) |
| Wingspan | 12.2 – 13.8 in (31 – 35 cm) | 12.2 – 13.8 in (31 – 35 cm) |
| Weight | 17 – 26 g | 22 – 30 g |
As the table shows, the sizes of males and females overlap significantly, with females just slightly larger on average.
How do black swift sizes compare to other swift species?
Black swifts are very small compared to most other swifts. The only species that come close in small size are the related chimney swift and the tiny palm swift. Some key size comparisons between black swifts and other swifts include:
- Black swifts have shorter wingspans than common swifts and white-throated swifts.
- Black swifts weigh only about half as much as white-collared swifts.
- Black swifts are shorter in length than fork-tailed swifts and sickle-winged swifts.
So in summary, besides the chimney swift and palm swift, black swifts are the smallest species in the swift family.
How do the sizes of young and adult black swifts differ?
When black swifts first hatch, they are quite small, weighing only about 10-12 grams. Their wings are not fully developed at this stage. Over their first few weeks of life, the young swifts grow quickly, putting on weight and growing longer wings.
By the time they are ready to fledge and take their first flights, juvenile black swifts are nearly the same size as adults. Their wingspans are similar, though their flight feathers may still be slightly shorter. The main difference is that juveniles weigh a bit less than adults, since they have less time to build energy reserves.
Typical Sizes of Young vs. Adult Black Swifts
| Measurement | Juvenile Size | Adult Size |
|---|---|---|
| Length | 4.7 – 5.3 in (12 – 13.5 cm) | 4.7 – 5.5 in (12 – 14 cm) |
| Wingspan | 11 – 13 in (28 – 33 cm) | 12.2 – 13.8 in (31 – 35 cm) |
| Weight | 15 – 25 g | 17 – 30 g |
How have black swift sizes changed over time?
There is no evidence that the sizes of black swifts have changed significantly over the past century. Their morphological measurements appear to have remained relatively stable and consistent.
Some factors that help explain their consistent size over time:
- No major habitat changes – Black swifts still nest in similar rocky crevices and behind waterfalls as they did historically.
- No overhunting or major population declines – Their remote habitat has protected them from major threats.
- No major climate shifts in their range – Temperate climates of western North America have been relatively stable.
Barring any major future habitat or climate changes, we would expect the small size of black swifts to remain consistent for the foreseeable future.
What size nests and crevices do black swifts use?
Given their small size, black swifts are able to utilize very small spaces for nesting. They typically nest in narrow crevices on steep, rocky cliffs behind or adjacent to waterfalls. The narrowest openings they can squeeze into are around 1-2 inches across.
Some key facts about black swift nesting spaces:
- Openings can be circular or crescent/half-moon shaped.
- They nest in crevices up to around 4 inches tall but can use spaces as short as 2 inches.
- Depth of crevice can range from 8 inches to several feet deep.
- Nests are often completely enclosed except for the narrow entrance.
The small size of black swifts allows them to take advantage of nesting sites that are inaccessible to larger birds. Their specialized ability to cling to vertical rock walls also aids in utilizing tiny crevices.
Typical Black Swift Nest Dimensions
| Measurement | Range |
|---|---|
| Entrance width | 1 – 2 inches |
| Height | 2 – 4 inches |
| Depth | 8+ inches |
Conclusion
In summary, black swifts are diminutive birds with total lengths of 4.7 to 5.5 inches, wingspans of 12.2 to 13.8 inches, and weights of just 17 to 30 grams. Males and females are very similar in size. Compared to other swift species, black swifts are on the smaller end of the spectrum.
The tiny size of black swifts allows them to utilize inaccessible crevices for nesting, with entrance widths as narrow as 1-2 inches. Their small size has remained consistent over time and allows for their specialized nesting behavior.
