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Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 9:23 am
by nzsam
Yesterday I discovered the pair of Gull-billed Terns that have frequented Awarua Bay intermittently over the past three years or so, now have a nest with three eggs in it. They are on the edge of a small white-fronted tern colony which is adjacent to a huge Southern black-backed gull colony.

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 12:17 pm
by Jim Kirker
Might be best to keep an eye on them from a good distance away - they are quite sensitive to disturbance as this study showed.
"The nests in the colony are relatively dispersed, and several small colonies tend to form rather than one large one. It was clear that the disturbance caused by my activities was partially responsible for this nest distribution. For example, during 1972, my presence appeared to prevent the establishment of a colony in what had been the preferred area in 1971. When I moved my blind to the area that was becoming occupied, further nesting ceased and nesting began
in a still less suitable area."

https://sora.unm.edu/sites/default/file ... -p0016.pdf

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 12:28 pm
by Colin Miskelly
Congratulations Glenda - great find!

Please submit this as an Unusual Bird Report, as a first breeding record for New Zealand

https://www.osnz.org.nz/webforms/online-reporting-form

If you are able to monitor the outcome without disturbing the birds, it would also be good to see this written up as a short note for Notornis

Nga mihi
Colin

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 1:10 pm
by nzsam
Yes I will submit a UBR for this shortly. I will not be able to get back in the next fortnight due to work, but I gave the heads up to the Southland Birds New Zealand members last night in the hope they can monitor things in the meantime.
Glenda

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 1:45 pm
by Adam C
Great stuff!

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 3:51 pm
by Adam C
As somebody pointed out on the facebook post these chicks will be pretty vulnerable to the near by Black Back Gull colony. Gone in seconds if discovered. Fingers crossed.

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 5:17 pm
by Jim Kirker
Their nesting near the BBG colony could be an adaptation to protect against predation - more birds looking out for predators and alarming the rest. Harold Sears in the paper inked to above saw eggs and chicks predated by gulls, so the BBGs possibly are a real threat. He also reported that "Diving terns also occasionally punctured my fiber-board helmet with their bills; a peck of this intensity is probably a real deterrent to potential predators."

Re: Gull-billed Terns Nesting

Posted: Sun Dec 22, 2019 9:07 pm
by Phil Rhodes
Well done Glenda excellent photos and another record for Southland. Even more satisfying that the first sighting of GBT was at the Invercargill Airport back in the 1950s. I saw them last year at this site about the same time and they were up with the WFT and the lone Caspian pair and possibly attempted to nest then. As Adam and Jim mention the large SBBG colony could be an issue, DoC were looking at removing these birds several years ago but still has not happened. The easy access from the road could also be an issue, there has been motor bike tracks on there quite often. Fingers crossed they manage to raise at least one chick. The terrible weather conditions at the moment won't be helping. I will try and get out there a few times during the Christmas break.

Re: Gull-billed Terns Nesting

Posted: Mon Dec 23, 2019 12:10 pm
by David Melville
A great record Glenda - well done! The issue of Black-backed Gulls is an interesting one - we regularly have good numbers of Variable Oystercatchers nesting close by BBGs at Motueka Sandspit - the nests are easy enough for a human to find by just following the VOC's footprints so I imagine that gulls would have no difficulty either. This year there has also been a good sized colony of White-fronted Terns, Red-billed Gulls and Black-billed Gulls on the Sandspit a few hundred m from nesting BBGs - apparently with no major adverse effects.

Re: Gull-billed Terns Nesting

Posted: Mon Dec 23, 2019 2:04 pm
by Jan
Caspian Terns used to nest next to Bback Gulls at lake Ellesmere when there was a colony near to Embankment Rd years ago. It has since moved elsewhere.