The
background to our recent visit to Lady Musgrave Island on the Great Barrier
Reef (GBR) was given in Coral Cay Island Birds – Great Barrier Reef – Part 1
Background.
We saw 6
species of terns on Lady Musgrave Island. The Black Noddy was covered in the Part
2 post. The other 5 tern species present on the island were Crested, Lesser
Crested, Roseate, Black-naped and Bridled.
The Crested
Tern is the most widespread and common tern to be found in Australian coastal
waters. All of the other tern species we saw on Lady Musgrave Island are relatively
uncommon and are more or less tropical species confined to tropical waters and
therefore rarely found in southern Australia, particular along the coastline of
my home State Victoria.
Bridled Tern (Onychoprion anaethetus)
Bridled
Terns are similar to Sooty Terns and have a similar range in Australia. There
were at least 20 pairs of Bridled Terns observed on Lady Musgrave Island in the
early stage of breeding. Most birds were seen in pairs with many at nesting
sites and courtship displays were also seen.
The Bridled
Terns were nesting along the sandy beach not far above high tide level in a
number of situations including under beach washed tree trunks and low dense
shrubs and in long grass. This tropical tern breeds every six to seven months.
Bridled Tern above Tournefortia argentea (tree heliotrope) bush. |
Same bird as above a second or two later. |
Black-naped Tern (Sterna sumatrana)
This small
elegant tern is exclusively tropical and marine, resting and breeding on coral
reef cays and feeding mainly on small fish taken in adjoining tropical seas.
There were
possibly 50 to 60 Black-naped Terns on Lady Musgrave Island when we were there.
They did not show any signs of breeding however many gathered together at the
top of the beach and at times fights broke out among some birds – perhaps this
was a preliminary stage to forming pairs ahead of breeding which mainly takes
place between October and December. One bird was seen carrying a small fish –
fish flights and offerings to females are a part of courting for many tern
species.
A small gathering of Black-naped Terns on coral rubble at the top of the beach on Lady Musgrave Island. |
The pink
blush visible on the birds in the above photo is mentioned in only the Pizzey
and Knight field guide. While subtle it was quite obvious so it is somewhat surprising
none of the other three popular Australian birding field guides mention this
feature.
Periods of relative peace were punctuated by fierce squabbles among some birds. |
The black napes show clearly on both the attacker and the attacked in this shot. |
There was plenty of space for resting birds – this altercation most likely relates to competition for a mate and not roosting space on the beach? |
In flight, the Black-naped Terns appeared a brilliant white against the intense blue tropical
sky.
Roseate Tern (Sterna dougallii)
Roseate
Terns are another tropical waters tern rarely seen down south. Only one pair
was seen on Lady Musgrave Island. One of the Wardens on the island said more
were expected to arrive shortly to breed there. I encountered the pair on a
number of occasions, usually resting close to the shoreline among Crested
Terns. They were very wary so I could only get a couple of long shots of them.
Based
on the full black cap and red and black bill this pair in the photo below are in breeding plumage/condition. Non
breeding birds have all black bills and a white forehead. The bird on
the right has a silver band on its left leg.
Lesser Crested Terns (Thalasseus bengalensis)
Once again this
is another tropical waters tern not found down south. The Lesser Crested Tern
looks very similar to the much more common Crested Tern however it is easily
identified by its noticeably smaller size and orange bill – the Crested Tern’s
bill is yellow.
Only one
pair were found on Lady Musgrave Island. They associated closely with the
larger and closely related Crested Terns. The Lesser Crested could easily be
overlooked among a large flock of Crested Terns so it is always a good idea to
check carefully through a large flock of terns to see what other species might
be lurking within their ranks.
One of two Lesser Crested Terns found on Lady Musgrave Island. Note the white flecks on the forehead – this bird is probably moulting to breeding condition, that is to a fully black cap. |
Crested Tern (Thalasseus bergii)
There were
200 to 300 Crested Terns on Lady Musgrave Island with most adults in breeding
plumage. There were also a few juveniles and non-breeding adults. Some rested
on the sand spit at the NE end of Lady Musgrave Island and others on a couple
of defunct structures in the lagoon used in the past for tourists to view the
underwater world of the lagoon without the need to enter the water.
A small section of a Crested Tern flock on the sand spit at Lady Musgrave Island. The two smaller terns in the foreground are White-naped Terns. |
The black shaggy feathers at the back of the head on display here are not really a true crest. The dark bird is a Black Noddy. |
For anyone
wanting to see a range of tropical tern species in one place, a visit to a coral
cay island on the Great Barrier Reef is a must.
Post No.4
will cover Wedge-tailed Shearwaters that were breeding on Lady Musgrave Island
and Brown Boobies which were breeding on nearby Fairfax Island.
No comments:
Post a Comment