The birds of Christmas Island
The Indian Ocean Territory of Christmas Island is home to many famous endemic bird species including the Golden Bosun, Frigate bird and Abbott's Booby. The island is where I first developed my love for observing bird behaviour.
This love for birds is shared amongst many of my vagrant human friends.
Quick ornithology lesson - 'vagrant' refers to one who has strayed from her usual migratory path
A wonderful thing about birds is that you can learn so much through simple observation. Their anatomy is carefully designed to suit their needs - for example, the size of their bill gives clues to the type of food they eat, their wingspan varies depending on the distance or speed of flight they need, and the colour of their plumage is unique to their geography. Watching a bird's behaviour involves taking note of whether they're alone or part of a flock, are they flying high in the sky or skipping through underbrush and over time you can observe for yourself, their evolutionary lifestyles - are they migratory birds, do they feed on insects in the grass or dive for fish in the ocean?
In medicine, observation is a clinical skill learnt in the early years of uni but often supplanted by diagnostic tests like pathology or imaging. It's something I enjoy with remote work where tests are not easily available and we're forced to recall those rudimentary skills. For example - what is the gait (characteristics of someone's walk) telling us about where someone's pain is? Does their foot drag because they have a spinal nerve impingement? Does their hip drop because they have proximal muscle weakness? Do they toe walk because they have tight calves from distance running?
Back to birds...
Christmas Island is famous for the beautiful Golden Bosun who I've never caught a close-up photo of, but you can find here at the Natural History Association. It soars high in the sky with a white tail and two long (35cm) golden tail streamers. They are often seen in pairs painting graceful ribbons in the sky. There is a white-tailed morph, locally called the silver bosun who surfs head winds along the cliffs. A particular mother silver-bosun has spent the last few years nesting in the hole of a tree beside the boat ramp.
The island is also home to the Christmas Island Frigatebird and the Great Frigatebird that are albatross-like birds with wingspans up to 230cm wide. The Great Frigate bird has a bright red pouch under its neck that swells into a shiny balloon when flirting. At the end of a fishing day, Frigatebirds gang together to swoop and hijack fish from returning Booby.
Booby birds are cousins to the flamboyant Blue-footed Booby of the Galapagos Islands. Christmas Island has three members of the Booby family - Red footed, Brown and Abbott's Booby. Red footed Booby can be seen through breeding months as white cotton, dotting the cliff-scape with nests built into coastal trees. Parents fly out to ocean each day to fish, reaching distances up to 150 km and often cruising alongside fishing boats. They return home in the evenings to regurgitate a meal for their babies. Brown Booby nests are found on the ground of rocky clifftops and it's possible to walk close to the fluffy white babies. When people approach, the parent Booby tends to fuss and rearrange fallen sticks around the nest. The endangered Abbott's Booby is named for its black face mask surrounded by white plumage that breeds only on Christmas Island.
Booby birds are my favourite winged family. Their eyes angle forward (unlike other birds with eyes on the side of their heads) to allow them more precise binocular vision for fishing. This also means that as they fly past you they distinctively turn their head to have a good gawk. When they dive they draw their body and wings into a torpedo shape to reduce wind-drag and water resistance, reaching underwater depths of 25m.
Shared parenting is important to the Booby, with both male and female birds taking turns to incubate their eggs. Unlike other birds that pluck feathers from their abdomen forming naked 'brooding patches' to warm their eggs when they sit on them, Booby birds' use their feet. Their webbed toes become swollen and hot ,creating an incubation shroud.
The island is also home to the Hawk Owl, Goshawk, Imperial pigeon and Emerald Dove - a glossy green-purple bird that lives on the rainforest floor and prefers walking to flying and feeds on fallen fruit.
The common Noddy is found around the cliff undersides and is a feisty little bird that likes to swoop as you kayak by.
Another favourite of mine is the Australian Kestrel who I'm yet to catch a photo of, but I've seen all around the country. This little raptor (bird of prey) tends to take up residence on its favourite perch, antennae or rooftop, spy the victim and take flight. Then after a lazy circle will hover and with a few rapid wing-beats descend silently on its prey... usually a stray baby chicken ... Tragic and thrilling.