Red-billed Tropicbird (Phaethon aethereus) by Ian Montgomery

Ian’s Bird of the Week – Red-billed Tropicbird ~ by Ian Montgomery

Newsletter – 6/6/11

Last November a Red-billed Tropicbird was recorded on Lord Howe Island (http://aussiebirding.wildiaries.com/species/23736). This is the first Australian record and it is a long way from its closest breeding colonies in the Galapagos. I photographed this species in 2005 at another Ecuadorean site, Isla de la Plata (‘Silver Island’) so I thought I’d share it with you as Tropicbirds are among my favourite birds. Lord Howe Island, incidentally, has breeding Red-tailed Tropicbirds (http://www.birdway.com.au/phaethontidae/red_tailed_tropicbird/index.htm). Isla de la Plata is often called the poor man’s Galapagos as it’s a mere 40km from the Ecuadorean coast as can be visited on a day trip for about $40 and has some of the Galapagos specialties such as the Blue-footed Booby (http://www.birdway.com.au/sulidae/blue_footed_booby/index.htm).

Red-billed Tropicbird (Phaethon aethereus) by Ian Montgomery

The Red-billed Tropicbird is easily distinguished from the closely related Red-tailed by its white tail streamers and black barring on the back and wings (first photo). It is the largest of the three species with a body length of about 50cm/20in, tail streamers of at least another 50cm/20in and a wingspan of about 1metre/40in. The two tail streamer feathers are longer in the male and used in aerial display and may also be used as a rudder in flight. They are fragile, often broken (second photo) and are replaced continually.

The courtship display of the Red-billed Tropicbird starts with a number of birds flying around near the colony which is usually on a rocky cliff. A pair of birds may then separate from the flock and start synchronised aerobatics, as in the third photo. This time I’ve embedded the photos in the body of the email; if this causes any problems, eg with older email programs that don’t support HTML, just let me know ian@birdway.com.au and I’ll revert to attaching them.

Red-billed Tropicbird by Ian Montgomery

This display may lead to a choice of nest site (from the air). Tropicbirds have webbed feet and weak legs and can move only with difficulty on land, so the choice of inaccessible cliff sites is supposed to offer protection from terrestrial predators and allow easy take off.

They feed by diving for prey, often flying fish and squid, as do gannets and boobies and, like them, have air sacs in the head and neck to absorb the impact of hitting the water. The tropical waters in which they feed have low prey densities so they travel far and when not breeding lead a pelagic existence. They aren’t closely related to gannet and boobies; DNA studies suggest that they have no close relatives and Christidis and Boles (2008) place the three members of the Tropicbird family, the Phaethontidae, in their own order, the Phaethontiformes. The third and smallest species is the White-tailed Tropicbird, best known in Australia as the apricot-coloured morph found on Christmas Island and known locally as the Golden Bosunbird (http://www.birdway.com.au/phaethontidae/white_tailed_tropicbird/index.htm).

I’ve had an encouraging response to last week’s request for photos of Australian birds that I can’t supply, with about 60 species of the wanted list being offered. There are still 200 to go, so have a look at the update wanted list to see if you can help.

On the website, I recently changed my policy of not including captive birds under any circumstances and have added photos of a Malleefowl (http://www.birdway.com.au/megapodiidae/malleefowl/index.htm) and Little Penguins (http://www.birdway.com.au/spheniscidae/little_penguin/index.htm)  in tolerably natural-looking sets.

Best wishes,

Ian

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Ian Montgomery, Birdway Pty Ltd,
454 Forestry Road, Bluewater, Qld 4818
Phone: 0411 602 737 +61-411 602 737
Preferred Email: ian@birdway.com.au
Website: http://birdway.com.au

Lee’s Addition:

Ian made some interesting observations about the Tropicbirds:

• Have webbed feet
• Have weak legs
• Can move only with difficulty on land
• The choice of inaccessible cliff sites is supposed to offer protection from terrestrial predators and allow easy take off.
• When diving for prey air sacs in the head and neck absorb the impact of hitting the water.

Looks like these features add up to a neatly created design to provide for and protect the tropicbirds.

Then God said, “Let the waters abound with an abundance of living creatures, and let birds fly above the earth across the face of the firmament of the heavens. (Gen 1:20)

The Tropicbirds are in the Phaethontidae – Tropicbirds Family. There are only three species in the family and they are the only family in the Phaethontiformes Order.

More of Ian’s Birds of the Week – Click Here

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