28 December, 2015

Migrant of the Year

One of the highlights of this year has been the influx of migrant moths into much of the UK. The likes of Dark Sword-grass, Small Mottled Willow and, just recently, Syncopacma polychromella have all reached the garden from their continental breeding grounds for the first time. However, the prestigious Bill's Birding Migrant of the Year award has to go to the Bordered Straw which went from no garden records to six in the space of a few months.

The above two moths represent the 1st and 3rd records for the garden (the 2nd didn't stick around for a photo), and turned up towards the end of May at the same time as a wave of Striped Hawk-moths and Bordered Straws hit the south coast. All three had sustained varying degrees of wear and tear on their travels from southern Europe, and were easy to distinguish as individuals because they each had separate little chunks missing from their forewings.

August came, and with it a second wave of Bordered Straws. Whilst the May individuals had been pale and sparsely marked - characteristics associated with moths of desert origin - these new moths were noticeably darker in colouration and turned up without any signs of travel-induced damage to their forewing, indicating that they'd emerged locally - the home bred second generation from eggs laid by the pale individuals back in May.

The question of whether an individual is a 'true' migrant or the home-grown offspring of an egg laying migrant is a hard one to answer. As recorders we all like to hope that our moths have made the impressive crossing from across the channel, and luckily Bordered Straws are one of those species that give us some clues as to their origin through their forewing patterns! 

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