Methods
Cover: Monitoring Charadrius plovers in Andavadoaka, Madagascar, 2015 (photo by Luke Eberhart-Phillips)
How to catch waders? How to keep them safe until release? Which morphometrics are useful and how should they be measured? Which tracking tool to use: colour rings, leg flags, radio-transmitters, GPS PPTs or geolocators? How should all these data be analysed?
The choice of appropriate methods – from data collection to analysis – is fundamental for successful research. With more and more questions about shorebirds, it is of no surprise that wader enthusiasts keep expanding their toolbox, either by developing new methods or improving older ones. Since 1970, the Wader Study Group Bulletin (WSGB; and later Wader Study) has both facilitated and promoted the exchange of new methodologies for data collection and analysis, to use for the study of all aspects of waders’ lives, from migration and moult, to breeding and diet.
In the late 1970s, an important step was made in the colour marking field. After temporary leg flags made from PVC tape were used on Dunlin Calidris alpina by Goodyer et al. (1979), Nigel Clark (1979) described how to make permanent leg flags using ‘Darvic’ PVC sheets, a tool still used to this day. In order to attach leg flags, a procedure necessary to collect data to answer numerous questions, waders first need to be caught. Catching wild animals implies certain risks for their wellbeing, meaning that waderologists have used the WSGB to share their experiences and tips to minimise those risks. For example, there have been several papers on how to keep birds safely between catching and releasing (Bainbridge 1975, Minton 1993). To use all the data gathered during catching effectively, statistical analyses are required for correct interpretations to be made. Hence, to provide the readers of the WSGB with the correct tools, the editors invited Jeremy Greenwood to write a series of articles on basic statistics. The first part is included in this issue (Greenwood 1978). The rest of the series can be found here: 2, 3, 4, and 5).
In the 1980s, Ted Miller (1983) outlined the importance of knowledge about shorebird acoustics and introduced methods to analyse their sounds. Then, in 1985, Les Underhill provided the community with a new statistical model to study moult.
In the 1990s, the effectiveness of stomach-flushing to determine wader diets was assessed by Martin & Hockey (1993) and, because of the advent of technology allowing the remote tracking of shorebirds, Warnock & Warnock (1993) wrote an article reviewing the methods of attaching radio-transmitters to sandpipers, a subject that developed ever since. Later in the decade, Włodzimierz Meissner (1998) shared the Waterbird Research Group KULING’s experience of wader catching using walk-in traps and provided advice on their use, to help others optimise their own catches.
In the 2000s, Goss-Custard et al. (2002) discussed the errors associated with measuring the intake rates of waders, while McCaffery & Ruthrauff (2004) pointed to the difficulties in estimating shorebird nest numbers even after intensive search efforts. Details on how to build a mobile hide were published in 2003 (Székely et al. 2003), which was welcomed because studying breeding waders in the field almost always requires remaining unnoticed!
Laboratory techniques are essential to tackle several issues, and in the early 2010s, Dos Remedios et al. (2010) reviewed the major applications of molecular sexing and provided an essential guide on how to avoid common methodological pitfalls. In that same year, Clark et al. (2010) wrote about the use of light-level geolocators to study wader movements, a tool that has proved to be highly important in expanding knowledge on wader migration.
Methods have continued to be shared and discussed in WSGB and Wader Study, such as on the use of shorebird footprints and faecal droppings as ways of measuring foraging rate (Canham 2020). This Virtual Issue is merely a glimpse of the high volume of methods papers available, allowing a long-term perspective of changes in this domain as a way to celebrate the rich 50 year history of the (International) Wader Study Group.
(after going through the list of papers, make sure you see humorous note at the end!)
Curlew, Cramp, and Keeping Cages Ian Bainbridge Volume 16. 1975 Introductory Statistics 1 Jeremy J.P. Greenwood Volume 24. 1978 Leg Flags: Temporary Colour Rings L.R. Goodyer, F. Symonds & P.R. Evans Volume 25. 1979 Permanent Leg Flags Nigel A. Clark Volume 26. 1979 Sounds of Shorebirds 1. Introduction and Methods of Analysis E.H. Miller Volume 38. 1983 Estimating the Parameters for Primary Moult - a New Statistical Model L.G. Underhill Volume 44. 1985 The Effectiveness of Stomach-Flushing in Assessing Wader Diet A. Paul Martin & Philip A.R. Hockey Volume 67. 1993 Attachment of Radio-Transmitters to Sandpipers: Review and Methods Nils Warnock & Sarah Warnock Volume 70. 1993 Stress Myopathy in Captured Waders Clive Minton Volume 70. 1993 Some Notes on Using Walk-In Traps Wlodzimierz Meissner Volume 86. 1998 Beware of These Errors when Measuring Intake Rates in Waders John D. Goss-Custard, Ralph T. Clarke, Selwyn McGrorty, Rajarathinavelu Nagarajan, Humphrey P. Sitters & Andy D. West Volume 98. 2002 Using a Mobile Hide in Wader Research Tamás Székely, János Kis & András Kosztolányi Volume 103. 2004 How Intensive Is Intensive Enough? Limitations of Intensive Searching for Estimating Shorebird Nest Numbers Brian J. McCaffery & Daniel R. Ruthrauff Volume 103. 2004 Molecular sex-typing in shorebirds: a review of an essential method for research in evolution, ecology and conservation Natalie Dos Remedios, Patricia L. M. Lee, Tamás Székely, Deborah A. Dawson & Clemens Küpper Volume 117(2). 2010 The use of light-level geolocators to study wader movements Nigel A. Clark, Clive D. T. Minton, James W. Fox, Ken Gosbell, Richard B. Lanctot, Ronald R. Porter & Stephen Yezerinac Volume 117(3). 2010 Comparison of shorebird abundance and foraging rate estimates from footprints, fecal droppings and trail cameras Rachel Canham Volume 127(1). 2020
Among all the serious research shared in the WSGB, there has also been space for humour. The passage below, published in volume 24 (1978), and the glossary of cannon netting terms (please follow the link after the image) will surely make those using this method laugh.
A glossary of cannon netting terms, by Clive Minton