Here's the updated graph of the ratio of how many black fantails people are finding relative to pied birds throughout New Zealand.

The ratio of black to pied is supposed to increase as you travel further south. That's what we're seeing travelling from Wellington (-41º) down to Canterbury and Westland (-43º) but, oddly, the ratio is then swinging back towards more pied birds in Otago and Southland.

With more observations, we can be more certain about whether or not this is true. With more observations, we can also start looking for more detailed patterns, such as whether there are more black phase birds in more forested areas of New Zealand. Lots of observations made over many years will show us how black phase fantails are faring in the face of global warming.

The all-black fantails of southern New Zealand get replaced by all pied birds as you head north. This pattern is repeated in some other NZ birds, like the variable oystercatcher. As things get warmer, there are fewer advantages to being black.

Below is a graph of our results so far (as of 21 November 2014). (The spike at 42 degrees south just means we need more observations to get a more accurate estimate of the proportion of black to pied birds at that latitude.)

We're interested in getting heaps of observations of fantails including whether they were pied or black phase. This will allows us to better understand how the ratio of black to pied changes throughout New Zealand and how it shifts in landscapes with less forest and over time as New Zealand's climate continues to warm.

Feel free to add a comment here if you've got something to say about this project.