Spring is here!

By NZ Bird Atlas team September 9, 2019
Welcome swallow (Image courtesy of Dan Burgin)

The first of September is New Zealand’s first official day of spring, and with that the first winter survey season of the New Zealand Bird Atlas is now complete, and our first spring survey season has now started.

A key aim of the New Zealand Bird Atlas is to carry out a complete survey of the birds occupying each 10 x 10 km grid square during each of the four seasons of the year over the next five years.  With this in mind, the 1st September represents a “reset” in our survey efforts, and is the cue for all of our participants to get out and re-survey as many of the grid squares that were covered during the preceding three months, and to take advantage of the longer days to push further into our backcountry and begin surveying squares that we haven’t yet managed to get to.

When it comes to re-surveying grid squares that you’ve already covered during the winter months, your aim should be to record observations of all of the bird species likely to present in these same squares during the months of spring.  This will involve a combination of confirming which of your winter bird species are still present in your grid square in spring, as well as recording the presence of any bird species that you hadn’t encountered during the winter months.  And this could be due to a number of reasons.  As the days lengthen and the summer breeding season approaches, a number of our bird species that have been relatively quiet during the winter months begin to sing, making them much easier to detect.  Depending on which grid square you happen to be surveying, you may notice the arrival one or more spring migrants that have been absent over the winter months, including our two cuckoo species, inland-breeding waders such as banded dotterels and wrybills, and seabirds such as Hutton’s or sooty shearwaters .  In addition to these annual migrants, the changing seasons also trigger large-scale shifts in the distribution of a number of our land birds, including fantails, kingfishers, pipits and welcome swallows as they disperse back inland from their preferred wintering habitats in our coastal lowlands.  All of these changes demonstrate why it’s important for us to re-survey our grid squares each season, so that we capture all of these seasonal changes in bird distribution as part of the New Zealand Bird Atlas.

To make it easier to plan your spring atlas surveys, we’ve made some important changes to the New Zealand Bird Atlas eBird portal to make it easier for you to create season-specific summaries of atlas survey effort.  Perhaps the most important change is that we’ve now made it possible to switch between the four seasons when viewing the Atlas effort map, using the “Date” menu at the top of the map.  When you first open the effort map, it will display our total, cumulative year-round survey effort for the entire country, but if you click on the “Date” menu, you can change the map to display each seasons’ cumulative survey effort.  When it comes to planning where to go atlasing in spring, we recommend that you change the effort map’s date setting to “Spring (Sep-Nov)” to create the best view of where the gaps in our spring survey coverage are.  In a similar vein, our species distribution maps in the New Zealand Bird Atlas portal can also be changed to display either the year-round distribution of species observations, or to display the distribution of observations collected within a particular season.  A third change that we’ve made to the atlas eBird portal is to add this ‘season’ function to the “explore New Zealand” summary page to enable you to create seasonal summaries of cumulative atlasing effort, including the number of checklists submitted, number of active atlasers and number of bird species observed in each season.

Now that our first winter Atlas season is complete, we’ve also been fielding a few questions regarding how and when grid square statuses on eBird will change from “incomplete” to “complete”. As many of you will have noticed, we only display a single grid square status for each square, and currently they’re all set to “incomplete”. This status will be updated at the start of each season by the National Atlas Team, so the status that you can see on any given date will tell you whether or not the grid square has been completely surveyed in the atlas season in which that particular date falls. This being the case, the status of all grid squares will remain “incomplete” until the beginning of our second winter season on the 1st June, 2020. On that date, the status of a number of our grid squares will change to “complete”, so that our atlasers can see which grid squares were completely surveyed during our first winter season, and can therefore re-direct their survey efforts during their second winter survey season accordingly.

Happy atlasing everyone!