Before & After: The maturation of a Red-legged Honeycreeper

[Bill Holsten]

The male Red-legged Honeycreeper starts out looking very much like a female, and then progressively molts through a "patchwork quilt" stage and ultimately into the deep blue bird we see in the text books. The intense red legs are a constant throughout this process. The three images shown here were taken in a single afternoon last January in a private yard in northern Costa Rica on a photography workshop with Doug Brown and Greg Basco. The bird in the first image is just beginning to molt. The bird in the second image is well along in the process. The bird in the third image has completed the process.

EOS 7D, 300mm f/2.8 + 2X

All comments welcome.

[Bill Holsten]

Here is the second image.

[Bill Holsten]

And here is the third image.

[Tom Redd]

Bill, beautiful images, thank you for the education on these incredible birds. The second image is incredible.

[Tom Rambaut]

This bird is just amazing!

[Stu Bowie]

Bill, thanks for sharing this. The pose in the second image shows it off best, as its more side on, showing the wing. Incredible colours.

[Nancy Bell]

Very interesting series of the molting sequence. That blue is a very intense color. You might consider a little "eye doctor" work to reduce some of the glare.

[Jeff Cashdollar]

Not sure which is better the education or photography - (both grand). Thanks for sharing - keep em coming.

[John Chardine]

Great to see Bill.

We tend to take it for granted when we see birds literally changing their clothes every year. They do an amazing thing when they moult their feathers and grow new ones in, and the process takes a lot of energy and nutrients.

In evolutionary terms there are several reasons for moult, but the likely primary purpose is to replace worn feathers. A bird's plumage is critical to its survival- it keeps the bird warm and dry and allows flight. Feathers are made of β-keratins, the protein strands of which are woven into sheets and bonded to form structures like feathers. Our finger nails are made up of keratins too. Though tough, keratins wear over time, and feather tips in particular are vulnerable to wear. Unlike fingernails, feathers do not keep growing from the base so this wear cannot be replaced this way. Instead, the whole feather is dropped and a new one grown in it's place- the process of moulting. This prevents the bird from slowly losing its ability to stay warm and dry and fly due to feather wear over time.

Probably secondary to this primary function, birds often take the opportunity during the moult to change their colour as this honeycreeper so nicely illustrates. Why this is done is a huge subject but a common reason is for males to moult into a bright plumage before the breeding season to attract mates. Curiously we think of this bright breeding plumage as the "correct" plumage for a species but in fact it's the often duller, non-breeding plumage that should be considered typical of the species. In ornithology, this non-breeding plumage is called the Basic plumage, and the breeding plumage is referred to as Alternate. Birds usually spend more time over a year in their Basic plumage and that plumage has evolved to optimise the survival of the individual in terms of things like feeding efficiency and predator avoidance. Although the Alternate plumage often makes males more attractive to females it does not come without costs- it can make them more conspicuous and therefore more vulnerable to predation, and may make it more difficult to stalk their prey.