The 2010 Hamilton Butterfly Count (7th annual)

Wild Indigo Duskywing
Photo taken by Dean Gugler in Hendrie Valley

I have decided to fix the date of the butterfly count to the first Sunday in July. It is possibly not an ideal time as some species of skipper in "coolish" years may not yet fully be on the wing. But no date is perfect. Fixing it later in July will make it much more difficult to record several early species that are often missed even in early July such as Juvenal's Duskywing, Long Dash, and Silvery Blue. In concert with Brenda Van Ryswyk who organizes the Hamilton Odonata Count (dragonflies and damselflies), we have decided to make the first weekend in July as our "insect weekend". The dragonfly and damselfly (odonata) count will be on Saturday followed by the butterfly count on Sunday. Not ideal for some of you but most people preferred to have them on the same weekend.

This year's butterfly count was fair to good. We recorded 49 species which is about average over the seven years we have conducted this count. The weather in the month preceding the count was warmer than average and this certainly resulted in much different totals for many species as compared to 2009. In the count totals listed below, I have listed some of the 2009 totals (in bold) to show examples of this, shown most obviously in the number of European Skippers. This skipper is usually the most common butterfly by a wide margin but in 2010 we recorded only 10% of the 2009 total. Also the Marsh Eyed Brown total was just 20% of that in 2009. For both of these species the likely explanation for the drop in numbers is weather. Both of these species very likely emerged much earlier in 2010 and were largely "spent" by count day. This also applies to other single-brooded species such as Hobomok Skipper and Little Wood Satyr. Additionally this can be seen in the first brood of species such as Eastern Comma, Mourning Cloak, Viceroy and Red-spotted Purple. On the flip-side, the warm weather caused some species to be more abundant as it brought the peak of that species flight period into the count window. This is exhibited by the Common Wood Nymph and Tawny-edged Skipper (2nd brood).

There are some oddities on this year's count that are not easily explained. Where were the hairstreaks? In 2009, the only hairstreaks recorded were four Coral Hairstreaks and two Acadian Hairstreaks. That made some sense and I speculated in the 2009 write-up that the unseasonably cool weather in late June 2009 had delayed the emergence of most hairstreak species. However in 2010, although we did record four hairstreak species, we only recorded 6 individuals! This, despite the warm June weather and great count-day weather! This I cannot explain. I'll put it down to the "insect factor". Insect populations for both resident and immigrant species can fluctuate dramatically from year to year despite everything seemingly being equal. This may be the case with Common Sulphurs in 2010. This is usually a common enough species but it was the most numerous species on the 2010 count with 479 individuals being recorded. I guess everyone made a stop at their favourite alfalfa fields in their territories! One astute observer did note that, "The number of Common Sulphurs seems remarkable compared to other years. They seemed fresh and were likely of a second brood which recently emerged and were out earlier than normal".

There were only a few highlights on this year's count. I suppose the best butterfly recorded was the Common Buckeye. This was the second time this species has been recorded on the HBC. Rob Dobos saw two individuals in his area and I saw one in mine. Of course this preceded the unprecedented "invasion" of this species into the Hamilton Study Area (HSA). In 2010 it was the year of the Buckeye. They were found throughout the HSA in reasonably good numbers from count day until mid-October. Also very noteworthy on the count were the two Northern Cloudywings (two locations) observed by Brenda Van Ryswyk and Jerry Chapple. This was the first record of this species on the butterfly count. The Northern Cloudywing is a fairly uncommon species in the HSA, not always found in the same area year to year, and it is always a good find.

Of note this year was the reappearance of the Red Admiral. This immigrant species was not recorded on the 2009 count which seems bizarre for this assumed common species. This year we recorded 26 Red Admirals which seems about right I suppose. The "insect factor" again. I want to make note of the continued absence of the Aphrodite on the HBC. This species has never been recorded on this count and it has not been recorded in the HSA for several years. It used to be an uncommon, but regular species right in the heart of our butterfly count circle. It is too early to state that it is extirpated from the HSA (especially for an insect) but its continued absence is concerning.

In closing I would like to thank all of the participants on the 2010 count. Everyone got their results to me immediately after the count and answered all of the questions I had for them promptly. I very much appreciate your efforts. There are lots of other things one can do on a lovely summer's day.

2010 Results:

The count area for the HBC is a 7.5 mile radius circle which is centred exactly at the intersection of Kirkwall Road and 8th Concession at Kirkwall. This is the same circle that is used by the Odonata (dragonflies & damselflies) count as well. This circle has been divided into 8 areas.

Species	Count (brackets are 2009 count)
Silver-spotted Skipper	1
Northern Cloudywing	2
Wild Indigo Duskywing	1
Least Skipper	5
European Skipper	337 (3,748)
Peck's Skipper	19
Crossline Skipper	22
Tawny-edged Skipper	34 (8)
Long Dash	2
Northern Broken Dash	31
Little Glassywing	3
Delaware Skipper	6
Hobomok Skipper	3 (13)
Dion Skipper	1
Black Dash	9
Dun Skipper	20
Black Swallowtail	5
Eastern Tiger Swallowtail	15
Cabbage White	239
Mustard White	1
Common Sulphur	479 (22)
Orange Sulphur	20 (3)
Bronze Copper	2
Coral Hairstreak	2
Acadian Hairstreak	2
Banded Hairstreak	1
Hickory Hairstreak	1
Summer Azure	2
Eastern Tailed	8
Great Spangled Fritillary	73
Meadow Fritillary	1
Orange/Northern Crescent	83
Pearl Crescent	115
Baltimore	1
Question Mark	6
Eastern Comma	2 (26)
Mourning Cloak	5 (16)
American Painted Lady	7
Red Admiral	26 (0)
Common Buckeye	3
Red	6 (39)
Viceroy	1 (12)
Northern Pearly Eye	54
Marsh (Northern) Eyed Brown	34 (173)
Appalachian Eyed Brown	51
Little Wood Satyr	38 (153)
Inornate (Common) Ringlet	4
Common Wood Nymph	339 (103)
Monarch	66 (15)

Species: 49

Participants (18): Jerry Chapple, Barb Charlton, Rob Dobos, Marion Fletcher, Diane Green, Shirley Klement, Bill Lamond, Gord Lewer, Kevin McLaughlin, Sarie Nichol, Mary Pomfret, Norm Pomfret, Elaine Serena, Glenda Slessor, Brenda Van Ryswyk, Rob Waldhuber, Sara Waldron, Brian Wylie.

Parties: 7

Party-Hours: 43.5

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