A day of Cannon Netting
Jun. 9th, 2006 02:34 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
gemfyreThese photos are now almost a year old, but I figured I might finally get off my butt and post some. These were taking during a North-West Wader Study Group expedition cannon net carried out from Broome Bird Observatory - where I worked as an Assistant Warden last year. Except for three photos taken by my mum (who was visiting for a week), these were all taken by a guy named Rob Gegg, who attended the netting session and has a much better camera than my own.
The net is set on the beach early in the morning and/or during low tide. It's set on whatever is deemed the best beach for a catch by the team leaders. Today that beach was Two Dog Hermit on the northern shore of Roebuck Bay near Broome. A varied flock, consisting of mainly Godwits and Knots was spotted there in the previous days, and flocks tend to frequent the same beaches on the same tide cycle.
Before high tide, the team quietly makes their way to the hide (in the case it was in the rock formations at the base of the pindan cliffs). The team leaders usually place themselves in a closer hide with the detonator for the cannons and communicate with the main team via walkie talkies. Sometimes others are dispatched to "twinkle" the flocks. Twinkling involves slowly approaching a flock to make it move slightly - hopefully into the catching area. Only those with a lot of experience are allowed to determine when the best time is to fire the net. The flock should be a decent size to make it worth the effort, but not so large that it will take ages to process the birds - the longer they are in captivity, the more stressed they get. The birds must also be in the precise area, if they are straying to where the net edges will go, then you can't fire without risking the lives of many birds. The Australian Wader Study Group, which runs these expeditions has a record of a less than 0.2 percent deaths per netting, I think you're allowed 1% or something (could be lower), if you're consistently killing more birds than that you lose your licence, this in an exercise in banding and release, not retrieving dead specimens. The edges of the net can behead a bird and the weights at the corners of the net are hefty iron bars which move at speed once they're fired. Any fatalities are retrieved, examined and preserved for further research, so nothing goes to waste as such.
Anyway, on to the photos!
The entire gallery of photos can be viewed here - http://pics.livejournal.com/gemfyre/gallery/00009r1x?page=1
The crew hidden among the formations at the base of the cliffs. Once the net is fired we all have to take off as fast as our legs can carry us to the net. It's then moved out of the water to prevent any birds drowning, covered in shadecloth to reduce stress to the birds, and the birds are extracted and placed in hessian holding pens. It's a real buzz dashing to the net after hearing the cannons fire, but it can be hard going if the beach has soft sand or if you have to hide a long way from the net.
A flock of waders waits on the beach - out of the netting area. This flock consists of many Bar-tailed Godwit and Great Knots, but many other species mingle in too.
The flock is spooked (possibly by a Black Kite or White-bellied Sea Eagle) and takes to the air. They usually circle a few times and resettle almost exactly where they were.
Eventually (hopefully) the flock gets into the appropriate spot and the net is fired. Photos of this stage are rare because everyone is roped in to helping move the net from the water, set up the holding pens and transferring the birds from the net to the pens. Photographers are usually screamed at the put the camera down and help. A lot of swearing and yelling often goes on but you learn not to take it personally. The priority is to get the birds out of the net ASAP and if that requires a bit of yelling to get people to do what's needed quickly, then so be it. It's truly a form of organised chaos once the net goes off.
Eventually however all the birds are in the pens sorted by species and the net is spread out on the beach to dry. In the hot, wet season a shelter is set up for the people too, but this was a fine dry season day where the weather was mild and no sun shelter was required. Everyone can have a bit of breather now before getting into teams and starting to process the birds.
Processing consists of various tasks. The birds are given a metal band first up (or if they are already banded the band details are noted). Then the bird has it's beak length measured, it's head-beak length measured and it's wing length measured. It is also weighed and the moult stage is examined and noted as well as things such as breeding plumage. Then it given a coloured flag indicating where it was banded in the flyway. Birds banded with yellow were initially caught in North-western Australia. To facilitate further research, these flags now contain an alpha-numeric code. These can only be placed on larger waders but are designed to be read through a spotting scope - so an individual bird can be tracked without having to be recaptured.
Terek Sandpiper R1, being held by my mum just prior to release. The task you are assigned will depend on your confidence and experience. Only those with a lot of experience can extract birds from the net but anyone (even children) can be taught the correct handling procedure of a bird so they can ferry them to the holding pens or release them. Anyone is able to learn how to band, weigh and measure a bird if they want.
Banding a Greater Sand Plover. It looks vicious but the pliers are designed to go around the leg, so there's no risk of squashing the bird's leg.
Taking the head-bill length of a Great Knot.
Comparing the confusing wing moult patterns of Ruddy Turnstones.
Greater Sand Plovers. The bird at the back is in breeding plumage, the bird at the front isn't. Learning to ID these birds is quite a challenge. They all huddle together on the beach and are similar browns, reds and whites. You have 3 plumages to learn - breeding, non-breeding and juvenille. I learned to ID them based on a combination of beak shape and colour, plumage pattern, call and behaviour.
A Curlew Sandpiper looking pretty pleased to be free again. Before release you have to check that no raptors are in the area. Black Kites especially have learned that cannon netters can be a source of woozy waders that are easy to catch and eat. Strangely, they tend to walk away, rather than flying.
You can almost hear this Great Knot saying, "Yay I'm free!"
A lovely Ruddy Turnstone in full breeding plumage that I was about to measure. A second after this photo was taken however he gave a strong flap of the wings and escaped.
A Red-capped Plover, the second smallest of the bay's waders (the smallest being the Red-necked Stint). Also being held by me. I think Red-capped Plovers are the sanest wader in these parts, they stay in Australia all year round instead of embarking on a six day journey to Siberia every year to breed.
Eventually all the birds are processed and released (if a bird is injured it is kept by the local bird vet for observation before release, usually a little more rest in a quiet place is all that's needed). Everything is then packed up and hauled up the cliffs once again and everyone adjourns at the Observatory for a run down of the day's catch and info recorded.
The net is set on the beach early in the morning and/or during low tide. It's set on whatever is deemed the best beach for a catch by the team leaders. Today that beach was Two Dog Hermit on the northern shore of Roebuck Bay near Broome. A varied flock, consisting of mainly Godwits and Knots was spotted there in the previous days, and flocks tend to frequent the same beaches on the same tide cycle.
Before high tide, the team quietly makes their way to the hide (in the case it was in the rock formations at the base of the pindan cliffs). The team leaders usually place themselves in a closer hide with the detonator for the cannons and communicate with the main team via walkie talkies. Sometimes others are dispatched to "twinkle" the flocks. Twinkling involves slowly approaching a flock to make it move slightly - hopefully into the catching area. Only those with a lot of experience are allowed to determine when the best time is to fire the net. The flock should be a decent size to make it worth the effort, but not so large that it will take ages to process the birds - the longer they are in captivity, the more stressed they get. The birds must also be in the precise area, if they are straying to where the net edges will go, then you can't fire without risking the lives of many birds. The Australian Wader Study Group, which runs these expeditions has a record of a less than 0.2 percent deaths per netting, I think you're allowed 1% or something (could be lower), if you're consistently killing more birds than that you lose your licence, this in an exercise in banding and release, not retrieving dead specimens. The edges of the net can behead a bird and the weights at the corners of the net are hefty iron bars which move at speed once they're fired. Any fatalities are retrieved, examined and preserved for further research, so nothing goes to waste as such.
Anyway, on to the photos!
The entire gallery of photos can be viewed here - http://pics.livejournal.com/gemfyre/gallery/00009r1x?page=1
The crew hidden among the formations at the base of the cliffs. Once the net is fired we all have to take off as fast as our legs can carry us to the net. It's then moved out of the water to prevent any birds drowning, covered in shadecloth to reduce stress to the birds, and the birds are extracted and placed in hessian holding pens. It's a real buzz dashing to the net after hearing the cannons fire, but it can be hard going if the beach has soft sand or if you have to hide a long way from the net.
A flock of waders waits on the beach - out of the netting area. This flock consists of many Bar-tailed Godwit and Great Knots, but many other species mingle in too.
The flock is spooked (possibly by a Black Kite or White-bellied Sea Eagle) and takes to the air. They usually circle a few times and resettle almost exactly where they were.
Eventually (hopefully) the flock gets into the appropriate spot and the net is fired. Photos of this stage are rare because everyone is roped in to helping move the net from the water, set up the holding pens and transferring the birds from the net to the pens. Photographers are usually screamed at the put the camera down and help. A lot of swearing and yelling often goes on but you learn not to take it personally. The priority is to get the birds out of the net ASAP and if that requires a bit of yelling to get people to do what's needed quickly, then so be it. It's truly a form of organised chaos once the net goes off.
Eventually however all the birds are in the pens sorted by species and the net is spread out on the beach to dry. In the hot, wet season a shelter is set up for the people too, but this was a fine dry season day where the weather was mild and no sun shelter was required. Everyone can have a bit of breather now before getting into teams and starting to process the birds.
Processing consists of various tasks. The birds are given a metal band first up (or if they are already banded the band details are noted). Then the bird has it's beak length measured, it's head-beak length measured and it's wing length measured. It is also weighed and the moult stage is examined and noted as well as things such as breeding plumage. Then it given a coloured flag indicating where it was banded in the flyway. Birds banded with yellow were initially caught in North-western Australia. To facilitate further research, these flags now contain an alpha-numeric code. These can only be placed on larger waders but are designed to be read through a spotting scope - so an individual bird can be tracked without having to be recaptured.
Terek Sandpiper R1, being held by my mum just prior to release. The task you are assigned will depend on your confidence and experience. Only those with a lot of experience can extract birds from the net but anyone (even children) can be taught the correct handling procedure of a bird so they can ferry them to the holding pens or release them. Anyone is able to learn how to band, weigh and measure a bird if they want.
Banding a Greater Sand Plover. It looks vicious but the pliers are designed to go around the leg, so there's no risk of squashing the bird's leg.
Taking the head-bill length of a Great Knot.
Comparing the confusing wing moult patterns of Ruddy Turnstones.
Greater Sand Plovers. The bird at the back is in breeding plumage, the bird at the front isn't. Learning to ID these birds is quite a challenge. They all huddle together on the beach and are similar browns, reds and whites. You have 3 plumages to learn - breeding, non-breeding and juvenille. I learned to ID them based on a combination of beak shape and colour, plumage pattern, call and behaviour.
A Curlew Sandpiper looking pretty pleased to be free again. Before release you have to check that no raptors are in the area. Black Kites especially have learned that cannon netters can be a source of woozy waders that are easy to catch and eat. Strangely, they tend to walk away, rather than flying.
You can almost hear this Great Knot saying, "Yay I'm free!"
A lovely Ruddy Turnstone in full breeding plumage that I was about to measure. A second after this photo was taken however he gave a strong flap of the wings and escaped.
A Red-capped Plover, the second smallest of the bay's waders (the smallest being the Red-necked Stint). Also being held by me. I think Red-capped Plovers are the sanest wader in these parts, they stay in Australia all year round instead of embarking on a six day journey to Siberia every year to breed.
Eventually all the birds are processed and released (if a bird is injured it is kept by the local bird vet for observation before release, usually a little more rest in a quiet place is all that's needed). Everything is then packed up and hauled up the cliffs once again and everyone adjourns at the Observatory for a run down of the day's catch and info recorded.
