Migrant depatures

In my last monthly report I promised to look at migrant departures for 2018.  So here you are!

I have probably noted in the past that departures are a bit harder to deal with than arrivals.  This is not just a phenomenon of Carwoola or even Australia: Bill Oddie has noted in one of his tomes that spotting the last record for a year is a good way of getting your name in a birding clubs annual report.  It's not hard to see why:

• when you see a bird for the first time in a year it is easy to know its the first time; but
• if you see a bird on day x, late in the season; you don't know if you might also see one on day x+n (and 'n' might be quite a large number) so records have to be kept.

In the case of my records this means that not seeing a species in month X might mean they have migrated or just that no-one has reported one, and they might turn up next month.  So a definitive report can only be made at the end of the season.  However progress reports can be made about how the season is looking.

In this chart I have looked at the months in which migrant species have been spotted over the 11 years of this project and assessed which month is usually the last sighting.  This is marked in yellow in the graphic below.  I have then marked off whether the species has been seen or not in January or February and rated the status of the species.

I had noticed that cuckoos were very thin on the ground (or the tree or phone line) and that appears to be confirmed.  The only cuckoo recorded in February was a Horsfield's Bronze-Cuckoo.  The other 4 common Cuckoos had all vanished.  Possibly this is because the species they parasitise had given up nesting due to the dry January-mid February.

Overall, of the 12 species for which a rating is possible, 2 were seen after they would usually had gone, and 5 appear to have left early.  Arithmetic gives 5 species "on time" (so far). 

A further 9 species should get their status clarified in March.