Geolocators lead to better measures of timing and renesting in Black-tailed Godwits and reveal the bias of traditional observational methods
Creators
- 1. University of Groningen
- 2. University of South Carolina
Description
Long‐term population studies can identify changes in population dynamics over time. However, to realize meaningful conclusions, these studies rely on accurate measurements of individual traits and population characteristics. Here, we evaluate the accuracy of the observational methods used to measure reproductive traits in individually marked black‐tailed godwits (Limosa limosa limosa). By comparing estimates from traditional methods with data obtained from light‐level geolocators, we provide an accurate estimate of the likelihood of renesting in godwits and the repeatability of the lay dates of first clutches. From 2012 – 2018, we used periods of shading recorded on the light‐level geolocators carried by 68 individual godwits to document their nesting behaviour. We then compared these estimates to those simultaneously obtained by our long‐term observational study. We found that among recaptured geolocator‐carrying godwits, all birds renested after a failed first clutch, regardless of the date of nest loss or the number of days already spent incubating. We also found that 43% of these godwits laid a second replacement clutch after a failed first replacement, and that 21% of these godwits renested after a hatched first clutch. However, the observational study correctly identified only 3% of the replacement clutches produced by geolocator‐carrying individuals and designated as first clutches a number of nests that were actually replacement clutches. Additionally, on the basis of the observational study, the repeatability of lay date was 0.24 (95% CI 0.17 – 0.31), whereas it was 0.54 (95% CI 0.28 – 0.75) using geolocator‐carrying individuals. We use examples from our own and other godwit studies to illustrate how the biases in our observational study discovered here may have affected the outcome of demographic estimates, individual‐level comparisons, and the design, implementation, and evaluation of conservation practices. These examples emphasize the importance of improving and validating field methodologies and show how the addition of new tools can be transformational.
Notes
B3RLLL is not part of the repeatability analysis for first lay dates since it was also part of a GPS-tracking study; B3BYYY is included in this analysis because we know the laydate, but is excluded from further analyses because we don't know the fate of its first clutch. See uploaded files.
Funding provided by: Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003246
Award Number: 'Shorebirds in space' (854.11.004)
Funding provided by: Nederlandse Organisatie voor Wetenschappelijk Onderzoek
Crossref Funder Registry ID: http://dx.doi.org/10.13039/501100003246
Award Number: Spinoza premium 2014
Funding provided by: Anonymous donor*
Crossref Funder Registry ID:
Award Number:
Funding provided by: the Gieskes Strijbis Fonds*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Gieskes Strijbis Fonds*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Gieskes Strijbis Fonds*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Dutch Ministry of Agriculture, Nature Management and Food Safety *
Crossref Funder Registry ID:
Award Number:
Funding provided by: Province of Fryslân *
Crossref Funder Registry ID:
Award Number:
Funding provided by: University of Groningen*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Prins Bernhard Cultuurfonds *
Crossref Funder Registry ID:
Award Number:
Funding provided by: Van der Hucht de Beukelaar Stichting*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Paul and Louise Cook Endowment Ltd*
Crossref Funder Registry ID:
Award Number:
Funding provided by: BirdLife-Netherlands*
Crossref Funder Registry ID:
Award Number:
Funding provided by: WWF-Netherlands*
Crossref Funder Registry ID:
Award Number:
Funding provided by: Anonymous donor
Crossref Funder Registry ID:
Funding provided by: the Gieskes Strijbis Fonds
Crossref Funder Registry ID:
Funding provided by: Gieskes Strijbis Fonds
Crossref Funder Registry ID:
Funding provided by: Dutch Ministry of Agriculture, Nature Management and Food Safety
Crossref Funder Registry ID:
Funding provided by: Province of Fryslân
Crossref Funder Registry ID:
Funding provided by: University of Groningen
Crossref Funder Registry ID:
Funding provided by: Prins Bernhard Cultuurfonds
Crossref Funder Registry ID:
Funding provided by: Van der Hucht de Beukelaar Stichting
Crossref Funder Registry ID:
Funding provided by: Paul and Louise Cook Endowment Ltd
Crossref Funder Registry ID:
Funding provided by: BirdLife-Netherlands
Crossref Funder Registry ID:
Funding provided by: WWF-Netherlands
Crossref Funder Registry ID:
Files
Files
(148.4 kB)
| Name | Size | Download all |
|---|---|---|
|
md5:004028178bcb75af06ed34d0c62f24ab
|
11.6 kB | Download |
|
md5:d9acf744476522c3b0ed809c7a6430da
|
10.7 kB | Download |
|
md5:01c5b090c53f51c3b6849edbcbb4cfc4
|
10.7 kB | Download |
|
md5:e38e0864f6150095c131394acda0c172
|
9.5 kB | Download |
|
md5:1f211814760ac8aec1dc470459ce78ea
|
15.0 kB | Download |
|
md5:ac606bba4303bf5fb431896edc3c0e64
|
11.5 kB | Download |
|
md5:9e5aa2744bbb43a7dd20f6c721857d63
|
19.3 kB | Download |
|
md5:7d1d6283d1285656c5c1dac8353026b7
|
12.7 kB | Download |
|
md5:8bb80789c5b4077d7e11d04cd440d2f9
|
11.4 kB | Download |
|
md5:cd8dcf819248fe2233409657aa48b204
|
35.9 kB | Download |
Additional details
Related works
- Is cited by
- 10.1111/jav.02259 (DOI)