Gatekeeper

[Dave McCormick]

While at a butterfly talk last weekend, there was a mention of the gatekeeper and the puzzling thing that in Ireland its restricted to the coast from Co Wicklow to Kerry but this species hasn't seemed to move or expand and no one knows why since the meadow brown has expanded its range throughout Ireland and both feed on grasses, its odd that the gatekeeper isn't more like the meadow brown in distribution. Anyone have any theories to why the gatekeepr isn't expanded its range in Ireland? Could temperature be a factor?

[Essex Bertie]

Dave,
By the looks of the UK distribution map, the Meadow Brown seems to be able to cope better with a more northerly climate. Down south, it can be the only butterfly seen in light drizzle. It has an earlier and more protracted season, so it looks like the Gatekeeper just cannot get a foothold into the rest of Ireland. Maybe the southern coast is the only place that offers suitable microclimates where it can complete its life-cycle. It's noticeable that it is found further up the sheltered east coast than on the west. Maybe another half-a-degree of climate change will do the trick!

Where it is found in Ireland, does it occur at lower density than the Meadow Brown?

Rob

[Matsukaze]

I wonder if there is a possibility of it colonising Northern Ireland from Scotland?

[Dave McCormick]

Dave,
By the looks of the UK distribution map, the Meadow Brown seems to be able to cope better with a more northerly climate. Down south, it's can be the only butterfly seen in light drizzle. It has an earlier and more protrated season, so it looks like the Gatekeeper just cannot get a foothold into the rest of Ireland. Maybe the southern coast is the only place that offers suitable microclimates where it can complete its life-cycle. It's noticeable that it is found further up the sheltered east coast than on the west. Maybe another half-a-degree of climate change will do the trick!

Where it is found in Ireland, does it occur at lower density than the Meadow Brown?

Rob

Here is a map of gatekeeper in Ireland: http://www.butterflyireland.com/GatekeeperMap.htm I don't know much about the population densities but it seems in the same areas that meadow brown is faring better, map: http://www.butterflyireland.com/MeadowBrownMap.htm

The comma hasn't yet known to be breeding in Northern Ireland either but was seen last at one site in 2008, there was quite a number found this year, 6 were seen in Wexford on 18th March which is good sighting. Maybe it just isn't warm enough up north for gatekeeper or commas to breed here yet. However there was evidence to suggest (not proven) that comma may have been breeding in 2008 only at one site in east coast of Northern Ireland as one was seen on 7th May (spring brood) and again 3 on 23rd August a few miles away (summer brood).

I have started studying weather this year to see how it affects lepidoptera but don't have enough data to provide any sort of evidence on how it effects species yet. Here is climate report for Northern Ireland to show weather effects: http://www.metoffice.gov.uk/climate/uk/ni/print.html I don't know but maybe this could provide some sort of evidence. Climate of Ireland: http://en.wikipedia.org/wiki/Climate_of_Ireland

I wonder if there is a possibility of it colonising Northern Ireland from Scotland?

Copeland Islands of Donaghadee in North East Down is not very far from Scotland (possibly the closest part of Scotland is Portpatrick) but on a clear day you can see Scotland from them and on the Copeland Island Bird Observatory, it has been trapped quite a number of times with evidence that some moths are vagrants from Scotland, so I suppose its possible if it could travel over the sea, it could get here from there.

[Essex Bertie]

From the Meadow Brown sightings, under-recording doesn't look a problem. The Gatekeeper seems to have made some progress inland during years 1995-2004, but has then died out locally, so for me it is just on the northern limit of its range in the south of Ireland, much as the Lulworth Skipper is on the Dorset coast. Foodplant availability wouldn't be a barrier, but it can only sustain itself in primary habitats at a medium to low density, only colonising secondary sites inland in a run of warmer years?

Regards
Rob