Grey-tailed Tattler - Tringa brevipes
Introduction
This report summarises the data collected and survival analysis results for the Grey-tailed Tattler. It includes an overview of the number and type of records obtained through banding and resighting efforts, spatial and temporal patterns in detections, and outputs from mark–recapture survival models, conducted using modified Cormack-Jolly-Seber models adapted from Kéry & Schaub (2012), and implemented using JAGS. These analyses provide insights into apparent survival rates and recapture probabilities, helping to inform ongoing monitoring and conservation strategies for Grey-tailed Tattler within the East Asian–Australasian Flyway.
Species Profile
EPBC Listing: Marine, Migratory
EBPC information from: https://www.environment.gov.au/cgi-bin/sprat/public/publicshowmigratory.pl
In Australia, Grey-tailed Tattlers eat a variety of marine invertebrates, including worms, molluscs and crustaceans. In the lead-up to their migration back to Siberian breeding grounds, crabs may become a more important component of their diet. Crabs are caught in shallow water, with the tattler sometimes immersing its head completely to grab it in its bill. Occasionally they are weedled from burrows in the mud or sand, and are manipulated in the bill and thrown about to remove their legs, and they are then washed before being eaten.
Info from Minton (pers. comm.). For further reading on Grey-tailed Tattler, click here .
The data
By clicking on the tabs below, you are able to view capture summaries, locations and survival analyses of the shorebird species of your choice.
Please note: Juvenile proportion data is forthcoming and will be included in this document at a later date.
Sampling cluster locations
First capture locations of birds
Prior to survival analyses, we conducted a site fidelity analysis to determine major clusters of shorebird populations, and the amount of movement between each of these locations. Birds are assigned to a cluster from their first capture - this remains with them for the rest of their lives. Below is an interactive map, showing the major clusters at which individuals of the target species (here, Grey-tailed Tattler) were first captured in Australia.
Maps can be interacted with by scrolling in and out. Hovering over each coloured circle will indicate the name of the cluster/shorebird area, and the number of birds included in the circle. Measurements can be made using the tool in the upper left corner of the map.
All subsequent records by location
Many individual birds were captured or resighted repeatedly throughout their lives, so all subsequent captures are shown in the interactive map below. The colour of each record denotes the cluster at which each bird was first captured at (shown in the above map).
Site fidelity
The below shows the site fidelity measured in, and adapted from, Ross et al (in review).
The circle plot shown below shows all recorded paired sightings of individual Grey-tailed Tattler across all major shorebird sampling clusters in Australia. Each sighting pair shows a) where a bird was first scene, and b) where the bird was subsequently next seen. Colours in the circle plot correspond with the coloured locations shown on the maps of Australia. The size of each point on the maps indicates the number of observations (on a log scale). The circle plot summarises all recorded movements between site clusters (locations shown on the map) across the entire study period, including both within- and between-season transitions across a bird’s lifetime.
To understand the circle plots, each initial observation is shown at the cluster location closest to the outer ring: this is where a bird was first seen. The direction of the arrow shows the direction of movement, from where the bird was first seen, to where it was seen again: where the bird was reobserved is shown at the location set further in from the outer ring. Given that site fidelity is generally high, the vast majority of ‘movements’ show that birds were subsequently see in the same cluster as they were initially seen. The width of each colour band in the circle plots shows the number of birds observed and reobserved at each site, relative to all other sites at which the species is observed.
Finally, average site fidelity across the entire continent for each species with 95% confidence intervals for the entire combined population of Grey-tailed Tattler is shown below, with subdivisions showing age specific site fidelity: first-year juveniles/known immatures and adult birds (i.e. site fidelity for immatures was not explicitly calculated).
Capture/Resighting Summaries
In the interactive plot below, the numbers of records of both captured and resighted birds at each location is shown. Cluster names are the same as those in the maps in the previous tab.
A note on interacting with these plots (Click to expand)
- By clicking on the location in the legend, you can toggle data on and off.
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Several menu controls are available:
- Camera icon: download plot as a .png
- Zoom icon: By selecting zoom, you can click and drag on the plot to highlight an area you wish to zoom in on.
- 4-way arrow icon: Click and drag to move the plot around.
- Box select tool: click and drag to highlight and zoom in on certain columns that end in your chosen selection.
- Lasso select tool: This has the same effect as above, but draws a freehand shape rather than a box selection.
- Zoom in/zoom out tools: Clicking these buttons zooms in at a pre-determined rate.
- Autoscale tool: Resets the plot’s axes to the default automatic scaling upon first viewing the plot.
- Reset tool: Returns the plot to its exact initial appearance.
- Show closest data on hover: Shows exactly the data underneath the mouse cursor (specific colour within the column).
- Compare data on hover: Shows all data in the column to allow comparison (of all colours).
And in the below plot, the number of new individual Grey-tailed Tattler added to the sample population every year is shown, compared to the number of re-observed individuals every year. The plot above shows total numbers of records (including birds being resighted multiple times in a year), which results in far higher numbers of records than the plot below which only shows the number of individual birds. The plot below also shows the sites at which birds were first captured, and allows toggling of different sites on or off.
Metal bands versus Engraved Leg Flags
Throughout the banding programme, different strategies for marking birds have been used. Initially all birds were fitted with an Australian Bird and Bat Banding Scheme metal band only. In more recent years, engraved leg flags (in addition to metal bands) have increasingly been deployed in addition to metal bands at catching locations across Australia. The benefit of leg flags meant birds could be observed at a distance without being caught, making survival data easier to collect. Present day marking is almost, if not entirely exclusively simultaneous marking with leg flags and metal bands.
Most birds fall into one of the two categories, but a select few were recaptured after initially being fitted with a band, and then being given an engraved leg flag. As is apparent in the figure below, this group is notably smaller than either of the other two marking types.
Survival Analyses
In the following plots, we show the survival estimates of our modelling for the entire length of time which which the species has been sampled.
Overall Survival
The plot below shows survival across all of Australia combined.
Note: Annual survival estimates have been calculated for adult birds, whilst juvenile survival is averaged across the entire sampling duration. Juvenile in this instance refers to collective juvenile and immature birds, that is, birds that have not yet made their first northward migration. Because birds are juvenile/immature for a short period of time, there is relatively limited data so we have only generated an average.
Location-specific survival estimates
The plot below shows survival calculated for each major Shorebird Area at which birds are sampled. For clarity’s sake, all but one location have been toggled off, please click your chosen region/age group on the legend to view the data.
Recapture rates
The recapture rates shown below are those calculated by the model analysing all data across all locations. For clarity’s sake, all but one location have been toggled off, please click your chosen region/band type on the legend to view the data.
Age summaries - Juvenile Proportions
Coming Soon
Juvenile proportions and age summaries are in progress and will be incorporated into this document at a later date. Stay tuned!