OSNZ - Arctic wader colour-banding project

	OSNZ Arctic wader colour-banding project Godwit, knot and turnstone colour-banding
OSNZEO@slingshot.co.nz	HOME	AIMS	CONTACTS	PUBLICATIONS	WHAT'S ON?
OSNZEO@slingshot.co.nz	STUDIES & SCHEMES	LINKS	RARE BIRDS	ATLASSING	REGIONAL NEWSLETTERS

Arctic wader colour-banding project

Age-ratio scans on Bar-tailed godwits

Further information and results of these studies can be found on www.nzshorebirds.com

Arctic wader colour-banding project - Background

The OSNZ is studying the movements of Arctic-breeding waders in New Zealand, by individually colour-marking Bar-tailed Godwits, Red Knots and Ruddy Turnstones in both the North and South Island. The aim is to determine whether individual birds use a network of sites while in New Zealand, and if so, on what scale. Knowing whether sites or regions have discrete populations is important for interpreting local population changes, as well as informing management decisions. There is also interest from biosecurity agencies to determine the avenues of disease spread amongst birds in New Zealand, and northern hemisphere migrants are perceived as being potential sources of diseases entering the country. Birds are banded with individual colour-combinations that can be seen from a distance, enabling OSNZ members and other birdwatchers to contribute to the project by getting out and looking at birds legs.

What do the combinations look like?

	Birds will have two colour-bands on each tarsus (lower leg). The bands are white, yellow, red or blue. There will also be a single white or red leg-flag, which is made of the same material as the bands but projects out from the leg. The position of the flag is important! It can be on either the upper leg (tibia), or down with the colour-bands on the lower leg. If the flag is on the lower leg, you will need to note if it is above the bands, between them or below them. On this Bar-tailed Godwit (left) the four colour-bands and single leg-flag are clearly visible. The numbered metal band that is on the bird’s upper left leg does not form part of the combination.

How do we record the combinations?

The colour-bands are read from the upper band on the left leg to the lower band on the right leg. The godwit is therefore YRYY (yellow above red on the left leg, yellow above yellow on the right leg), with the white flag on the right tibia. In the field, it can be useful to draw a picture of the bands:


What else do we look for?

If the bird is a godwit, it can be possible to tell its sex. Females are quite a bit larger than males, with proportionately longer bills. Males go into much darker breeding plumage than females. If you think know the sex of the bird, put it down – this can help figure out who is who if the combination was not read fully. At some times of the year birds will be moulting into or out of breeding plumage. While giving a value to a breeding plumage score is somewhat subjective, the following scale is fairly robust: 1 = full non-breeding plumage 2 = mostly non-breeding with a trace of breeding plumage 3 = ¼ breeding plumage 4 = ½ breeding plumage 5 = ¾ breeding plumage 6 = mostly breeding plumage with just a trace of non-breeding remaining 7 = full breeding plumage Most birds will probably not do all their moult in New Zealand, but will leave on northward migration with some non-breeding plumage remaining.

When is the best time to look for bands?

The best time to look is not at high tide. Then birds are usually packed together, standing on one leg or sitting down, or hiding amongst vegetation. It is much better to scan for bands when birds are feeding, or moving around near a roost as the tide comes in. If you are going to look for bands, it pays to turn up an hour or two earlier than you usually would at a high-tide roost, or be prepared to stay until the birds move out onto the tidal flats to start feeding.

Is it still useful to report a partially-read combination?

Absolutely! This is especially true at sites away from the banding areas, where it can be important to know birds visited, even if we cannot figure out who it was.

How do we report sightings?

The best way (if you have a computer) is to fill in the band reporting Excel spreadsheet (below) and email it to us. Otherwise snail-mail will work. The spreadsheet may look like a lot of work, but some of it needs to be done only once. See below for an example of a filled-in sheet. The information we would like is:

Species – Use the drop-down menu, and fill in one form per species. Your name – Enter this each time you fill in a sheet. Your address / email / phone – Fill these in the first time you submit a record; you will not need to thereafter. Site name – e.g. Tapora, Kaipara Harbour. Habitat – A general description, e.g. shellbank roost, tidal mudflat, Sarcocornia saltmarsh. NZ grid reference / lat-long – If you have one of these to hand, enter it (again, once only). Date of observation Weather/light – e.g. Windy, poor light; Calm, sunny, bright. Time – Start and end of observation period. High tide time – If you know it. Stage of tide – Use drop-down menu: low / incoming / high / outgoing. Activity of birds – Use drop-down menu: feed / preroost / roost. Number of birds present – Total count, and use the pull-down menu to say if this is a count or estimate. Number of birds checked – How many did you get to check the legs of? Also use the pull-down menu to say if this is a count or estimate. Number of banded birds seen – Include all banded birds, even if you got only part of the combination. To enter the combinations: Put the bands in the left column (e.g. YRYY). If you are not certain of a band colour, put it in brackets with a question mark, e.g. Y(R?)YY. If you could not see a band at all, put a question mark in the combination, e.g. Y?YY, ??RB. The eight possible flag positions are given in the next columns. Put a ‘1’ in the correct column. You can then enter the sex and breeding plumage score if you have them, and make a comment about the bird. Any general comments can be typed in below the bands when you are done. There is a blank worksheet where you can enter and pre-sort records to figure out how many birds there were. Saving the file – A file name that is self-explanatory is best, e.g. “knot Phil Battley June 21 2004.xls”.

Sending the records in:
North Island Phil Battley Ecology Group, Massey University Private Bag 11-222 Palmerston North 4442 p.battley@massey.ac.nz 06 356 9099 ext. 2605	South Island Rob Schuckard Taipari Bay RD3 Rai Valley Marlborough Sounds rschckrd@xtra.co.nz 03 576 5371
For more information about the project, or if you wish to become more fully involved, please contact either Phil or Rob at the addresses above, or David Melville (Dovedale, RD 2 Wakefield, Nelson, david.melville@xtra.co.nz, Phone 03 543 3628).

BAND REPORTING EXCEL SHEET	EXAMPLE SHEET - AS ABOVE
Click on icon to download	Click on icon to download

Help needed - Age-ratio scans on Bar-tailed godwits

If you are out looking at godwits in October-November, can you help us and measure the proportion of juveniles in flocks along the East Asian-Australasian Flyway? Distinguishing juveniles from adults is generally easy (see below), and will help piece together answers to two questions: how many young godwits are there, and where are they? In recent years there has been concern about apparent low productivity of Bar-tailed Godwits, based on the low numbers of juveniles seen on the staging grounds in Alaska. In September 2004 in Alaska, while some sites had the ‘typical’ low numbers of juveniles, another site had about six times as many juveniles as adults! But what is not clear is whether this means that many juveniles routinely choose different locations to adults, or early departures of adults from a much bigger flock at that site left only juveniles remaining. In order to understand better the demographics and migrations of godwits, we need to enlarge the area over which we estimate godwit productivity. The most practical way to estimate how productive godwits have been is to count the numbers of juveniles and the numbers of adults in flocks on the non-breeding grounds. This is best done by visually scanning large numbers of birds. We are interested in age-ratio data on godwits anywhere along the Pacific Rim between Alaska and New Zealand (our interest is really in the subspecies baueri). While we believe adult godwits may migrate direct from Alaska to their non-breeding grounds in New Zealand and Australia, there is nothing to say that all juveniles do the same thing. By making scans through Australasia and Asia, we will learn a lot about how godwits migrate along the East Asian-Australasian Flyway.

Identification of adults and juveniles

Ageing of post-breeding godwits is done largely on the patterns and condition of the contour feathers on the wings, shoulders and back. Juveniles have strongly patterned mantle (‘back’), scapular (‘shoulder’), tertial and wing covert feathers, which are dark with extensive pale ‘notches’ coming in from the edges (Figure 1). This results in a spangled look. All the body and wing feathers are the same age, and the scapulars are slightly smaller than on adults, so juveniles look ‘neater’ than adults. Juveniles are also quite buffy in their overall colour, including on the breast, though this fades with time. FIGURE 1: Juvenile godwits, showing contrasting upperparts. The distinctive tertials are circled in the bird on the left. Note that some adults may still retain notched tertials after breeding.


Adults can be told by the wear on their feathers, their colouration, and their stage of moult. Postbreeding adults typically undergo some body moult on the staging grounds (sometimes a lot). Adults newly arrived on the non-breeding grounds can have a mixture of very worn, old breeding plumage feathers (often just the dark central part may remain on the upperparts) and new, grey-brown feathers with crisp edges (Figure 2). Some reddish plumage may be present on the underparts. The wing coverts of some adults can look at first like those of a juvenile, but closer inspection will show them to be frayed and worn. Juveniles have much fresher feathers in good condition. FIGURE 2: Post-breeding adult godwit, showing a mix of worn breeding (alternate) plumage and non-breeding (basic) plumage. Note the ‘toothed’ appearance of the worn wing feathers.


How long can the ages be distinguished?

Juveniles moult into their first non-breeding (basic) plumage some time after arriving on the non-breeding grounds. Experience in New Zealand indicates that juveniles can be easily distinguished throughout October and into November. Beyond mid-November ageing becomes more difficult, and while some birds can be told by retained juvenile tertials, age ratios can be unreliable if some first-year birds get overlooked. The best age ratios are when all juveniles have arrived but before the early-moulting juveniles start to look like adults. Total counts of juveniles, even without accurate age ratio data, can help determine when numbers have levelled off.

What data should be collected?

The basic data are counts of ‘adults’ (including previous years’ subadults if present) and counts of juveniles. Counts can take two forms: (1) Complete count If the flock is small enough, or laid out in such a way that all birds can be accurately counted and aged, count all adults and all juveniles. (2) Samples of a larger flock If the flock is too large to age all birds in it, repeatedly subsample different parts of the flock. Sample 50 birds from one part of the flock, then shift to another part and sample another 50 and so on. Aim for 10 non-overlapping samples of 50 birds. This becomes one scan. If time and birds permit, repeat the scans on the same flock (particularly if birds have flown and resettled) as many times as you are able/willing to do. Scans can be numbered by flock then scan (e.g. 1.2 equals flock 1, scan 2). *NOTE* Juveniles often end up together at one end of a flock. This is a problem for scanning when the whole flock does not get covered (e.g. if birds fly up part-way through a scan). If the ‘juvenile end’ has been scanned, the juvenile ratio is inflated; if the other end was scanned, the reverse will occur. It is crucial to spread subsamples throughout the flock, ensuring that the ends, edges and inner parts are all sampled appropriately. A field-sketch in your notebook may be useful for showing whether the flock has been sampled well enough, and whether juveniles are bunched (e.g. Figure 3). FIGURE 3: Example of a field sketch showing age ratio samples across a flock of godwits. Numbers are the count of juveniles and count of adults per subsample. In this flock, 900 birds were scanned. Note that most juveniles were found towards one end of the flock. Data from Bob Gill.


What other infomation is required?

Observer details, site, date, how many birds were present in total (even roughly), and any general comments. If scanning a flock somewhere we are unlikely to know the location of, please give latitude and longitude. For example: Big Sand Island, Tapora, Kaipara Harbour, New Zealand (36deg 22’53.9”S, 174deg 14’578.8”E). 25 October 2004. Observer: Feel Badly. Total number c. 1600, in two flocks. Flocks worked for 55 mins at high tide (1330-1425) in good light. Flock 1 (c. 900 birds) Scan 1.1: 12 juv; 488 ad. Scan 1.2: 5 juv; 495 ad. Flock 2 (c. 700 birds) Scan 2.1: 7 juv; 375 ad (flock flew when harrier passed by).

We would also welcome any information about godwit numbers anywhere along the Flyway on southward migration. Please feel free to contact us if you have any questions, comments, or information. Many thanks for your assistance!

Sending the records in:
Phil Battley Ecology Group, Massey University Private Bag 11-222 Palmerston North 4442 p.battley@massey.ac.nz 06 356 9099 ext. 2605