wgeoff

I've just had time to look over the new HK List and was very surprised to find a major change to the order of species.

Previously the List was water and seabirds (plus raptors) up to Murrelet followed by landbirds starting with Doves and going through to Buntings. This has been roughly the same since at least Avifauna. Although some changes in order within the sequence have occurred, the sequence of water/seabirds followed by landbirds has been maintained.   

Now in this 2020 List I find Nightjars, Swifts and Cuckoos have suddenly been promoted to immediately below ducks and very near the top of the list. I am going to find it quite difficult to read future reports based upon this new order.

I realise we are following the sequence given by IOC in their World List, and they have made this change in their current Master List v10.1.
Can someone please explain what the rationale for the order in their World List is? And what new ideas have emerged to allow such a major change in order?

Whatever they are, their lists are not going to be easy for ordinary birders to understand if nightjars are next to ducks.

Geoff Welch

[ Last edited by wgeoff at 30/04/2020 12:46 ]

wgeoff

As suggested, I have looked at the information on the IOC Website about their Master File 10.1.
My basic question is, why should nightjars come after ducks, which they don't seem related to, and not after owls as they were before.

The changes which have occurred in 10.1 came mostly from two papers - Prum et al. 2015 and Suh et al. 2016. I have copies of these papers if anyone is interested. They both contain similar information.

They are also very complicated to read if, like me, you are not familiar with scientific terminology so I hope I have got it right.

It appears that two factors influence the order of species in the World List and hence HK List.

The first is species similarity, mostly estimated using DNA sequencing. This is what we are familiar with. Birds are collected into like groups called Clades. So nightjars and swifts are in the same clade but not swallows.

But the second factor, and the main reason for the changes in version 10.1, is the ordering of Clades. It seems this is done by evolutionary order i.e. when it is estimated the earliest "species" in this group evolved. I'm not sure how this date is estimated but it is the one that has decided that the species group containing nightjars and swifts, and the species group containing cuckoos and doves, should go immediately after ducks and before all other species of waterbirds and landbirds.

This is best seen from the following diagram taken from Prum et al., which shows the species group order for the first half of the list compared to an evolutionary timeline given at the top   


     

This is the first time I have been aware of the evolution factor in the list. I guess there must be some way to put together groups of unrelated species but I'm not sure I like it.