February to early April (2016)
An Eastern Curlew on the mudflats of Roebuck Bay. Photo: Nigel Jackett
Early April, and the shorebird migration period is well underway here in Roebuck Bay. The first Greater Sand Plovers departed on March 7th to kick off the migration period, and the first Eastern Curlews soon started leaving as well. The curlews leave mostly at night, the haunting calls of the departing flocks filling the night air over the observatory. Now, in early April, other species including Bar-tailed and Black-tailed Godwit, Red and Great Knot, Curlew Sandpiper, and Pacific Golden Plover have joined the exodus, along with the migratory Asian subspecies affinis of Gull-billed Tern and White-winged Black Tern. Migration fever is obviously catching, as even the supposedly resident Black-winged Stilts have been observed lining up, showing the classic signs of pre-migratory restlessness (‘zugenruhe’), and even taking off and heading north! Who knows where they’re going!
Chucky the Kamchatka Leaf Warbler. The first seen on the Australian mainland. Photo: John Graff
The undoubted star bird of the period was a KAMCHATKA LEAF WARBLER, christened Chucky, who made the observatory grounds home for a period in mid-February. First found by the wardens on the 14th February, Chucky remained around the observatory until the 24th February, though he did perform a short disappearing act for a few days (much to the chagrin of at least one twitcher!). Chucky remained in situ long enough for most members of the annual Australian Wader Studies Group Expedition to catch up with this rare visitor to Australian shores. Of course, the AWSG Expedition’s primary interest was cannon-netting shorebirds in the bay. The aim of the catching is to flag or colour band birds to add to our knowledge of their migration routes and breeding areas, and to estimate breeding success for the season by determining the proportion of juveniles for each species caught. The catching was particularly successful this year, with catches made on every attempt in the bay, including catches of several tricky-to-catch and less commonly-caught species. Unfortunately, the juvenile proportions in the catches indicated that most of the more northerly-breeding species had very unsuccessful breeding seasons last year. We have our fingers crossed that they have better luck this season!
Probable Western Yellow Wagtail - race lutea. We welcome comments on this individual! Photo: John Graff
After some promising falls at the end of January, the rain largely disappeared and we are currently looking at one of the worst wet seasons for decades. Many of our wetlands, which dried in September or later last year, are dry or nearly dry already, so we have our fingers crossed for some late-season rain to top things up! Despite this, the birding has remained interesting as always. One of the highlights of the last month has been the number of Eastern Yellow Wagtails present, first on Roebuck Plains behind the observatory (including well over 300 present on the 6th March) and more recently at the sewage ponds in town (50+ in late March and early April). The numbers alone have been a highlight, but this has been enhanced by almost all birds being fully resplendent in breeding plumage. Most individuals have belonged to the ‘usual’ subspecies tschutschensis (or simillima, depending on your taxonomic preferences), but several of the green-headed subspecies taivana have also been seen, including a brilliant breeding-plumaged adult male on the plains. More recently, two breeding-plumaged males have been present at the sewage ponds with very limited pale eyebrows and may belong to one of the dark-headed subspecies such as macronyx. Whilst investigating the identity of these dark-headed birds, we also realised an unusual looking individual on the plains may in fact be a Western Yellow Wagtail, likely subspecies lutea. We’re currently seeking some more informed opinions on this bird.
The ‘usual’ interesting species in the bay have mostly been showing well, with Asian Dowitchers and Common Redshanks both present, some sporting their breeding colours prior to migration. At least one Common Redshank is a juvenile bird, so this individual may stay in the bay through the dry season. The Eurasian Curlew that has been seen periodically for over a year now was resighted by Adrian Boyle at Crab Creek on the 30th March, while the number of Broad-billed Sandpipers in the bay has grown significantly, culminating in a count of 302 at Wader Spit on our Shorebirds Tour on the 31st March. In late February, members of the AWSG Expedition also saw an Oriental Cuckoo in the mangroves at Crab Creek.
One of our local shorebird specialties - an Asian Dowitcher, in full-breeding plumage. Photo: John Graff
An Eastern Grass Owl takes flight in the late afternoon sun. Photo: Nigel Jackett
On the plains, things are dry. So dry that we can not only drive to the edge of Kidney Bean Claypan, but could also drive straight across the middle if we wanted to! The Yellow Chats are still around but they’ve only been seen in small numbers and have been tricky to find. The flipside is that they’re mostly in bright yellow breeding plumage, so have been worth the effort to find when we’ve been able to. Most of the plains waders have dispersed or started their journey north, but the occasional Oriental Plover, Oriental Pratincole and Little Curlew are still being seen, including a stunning breeding-plumaged Oriental Plover on our April course. Barn Swallows were present in numbers on the edge of the plains in February and early March, and two Red-rumped Swallows were seen amongst them on the 16th February.
Further afield, an Eastern Grass Owl was seen well on several occasions in grassland north-east of Broome in mid-February. Gallinago sp. Snipe have been present around town at the sewage ponds and the BRAC Ovals. Most have shown characteristics consistent with Swinhoe’s Snipe, and some dedicated photography efforts from one of our guests confirmed two birds on the ovals were indeed Swinhoe’s Snipe. However, one bird seen at the sewage ponds resembles a Pin-tailed – unfortunately we haven’t been able to confirm it. Also at the sewage ponds, the well-known Semipalmated Plover remained present until the 29th March, but now seems to have left for the north.