Explorations of an Ecologist: Tawny Crescent search at Carden Alvar

I have been on somewhat of a mission this spring and summer to work away at my Ontario butterfly list. While I have been interested in butterflies since the summer of 2011, it has only been during the last year or so that I have specifically targeted some of Ontario's range-restricted species. So far this spring I had already seen success with West Virginia White, Sleepy Duskywing, Dusted Skipper, and Mottled Duskywing, as well as a more widespread species in Common Roadside Skipper.

On Wednesday I finished up my Haliburton surveys by noon, and I had nothing on my schedule until evening amphibian surveys near the town of Durham in Grey County. This meant that I had a full afternoon and evening to make the drive across southern Ontario. Naturally I took a detour to the Carden Alvar for several hours in the early afternoon.

Alvar Road is one of my favourite places to explore at Carden, and despite the deep potholes filled with water I slowly navigated my trusty Mazda 3 along its length, beginning from the Victoria Road side. I periodically got out to stop and explore, as literally hundreds of butterflies were littering the roadway! Indian Skippers were once again the most dominant species and I must have seen over 200. It was insane.

Indian Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

One of the first non-Indian Skipper butterflies I saw was a Common Roadside Skipper, its wings in better conditions than the one I saw the previous day at Sandy Lake Road. It was one of eight (!) I observed at Carden, making me think that I was quite silly for targeting this species at Sandy Lake Road earlier.

Common Roadside Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

The other common skipper out in big numbers was Tawny-edged. This species is relatively widespread in southern Ontario, and is easily identified due to its small size and distinctive orange leading edge of the forewing from underneath.

Tawny-edged Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

An interesting tiger beetle caught my attention and I soon realized it was one I had not seen before. This is a Common Claybank Tiger Beetle, a species which prefers clay over sand, as its name implies.

Common Claybank Tiger Beetle - Alvar Road, Carden Alvar, Kawartha Lakes

Around the same time, this millipede was crossing the road. With the assistance of folks at iNaturalist I now know that this is Pesudopolydesmus canadensis.

Pseudopolydesmus canadensis - Alvar Road, Carden Alvar, Kawartha Lakes

A Common Grass-Veneer that touched down on to the roadside.

Common Grass-Veneer - Alvar Road, Carden Alvar, Kawartha Lakes

But while looking at moths, tiger beetles and millipedes was fun, the main reason I was at Carden was to search for a Tawny Crescent.

In Ontario we have three species of resident crescents (Phycoides). Both the Northern Crescent and Pearl Crescent are widespread, but the third species is the little known Tawny Crescent. The Tawny Crescent is much more restricted in its range, being found especially along the southern edge of the Canadian Shield in open habitats such as alvars and barrens. Tawny Crescents fly for a very short period (compared to the common two species of crescent), furthering the difficulty of finding one.

Northern Crescent and Indian Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

The identification of crescents is perplexing at best and many individuals are best left unidentified. There is still a ton to learn about these species! While Tawny Crescents are generally very dark from above, the most reliable way to tell apart a Tawny Crescent is by the colour and patterning of the underwings. This butterfly is a fairly typical Northern Crescent. From below, note the extent and colour of the patch on the rear margin of the hindwing. Generally this patch is brownish and extends quite a ways into the wing. Tawny Crescents meanwhile are straw-yellow from underneath, with much reduced coloration at the rear margin of the hindwing. The forewing also has a reduced pattern when compared to Northern Crescent.

Northern Crescent - Alvar Road, Carden Alvar, Kawartha Lakes

The above Northern Crescent was one of dozens that were seen along the roadsides. However numbers were lower than what I expected, making me wonder if I was still just a little too early for Tawny Crescent.

I shouldn't have worried since I came across two individuals that seem to check all the boxes for Tawny Crescent over the course of the afternoon! The first one was quite dark from above, giving off a classic appearance. From below, compare the coloration of the hindwing compared to the Northern Crescent, above, and you will see the differences. Also see that the Tawny Crescents have dark antennae tips, while Northern Crescents have orange tips (Pearl Crescents often have dark tips as well).

Tawny Crescent - Alvar Road, Carden Alvar, Kawartha Lakes

The second Tawny Crescent was a little further up Alvar Road, but still a good distance east of the intersection with Wylie Road. It was a bit trickier to identify from above, but its underwing pattern gave it away!

Tawny Crescent - Alvar Road, Carden Alvar, Kawartha Lakes

Tawny Cresent - Alvar Road, Carden Alvar, Kawartha Lakes

I slowly continued up the road, stopping quite often to scan the numerous skippers.

Common Roadside Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

My first Northern Cloudywings of the year were flying as well.

Northern Cloudywing - Alvar Road, Carden Alvar, Kawartha Lakes

While we are on the theme of drab, brown butterflies - duskywings were flying in low numbers and included both Columbine Duskywing and Juvenal's Duskywing.

Columbine Duskywing - Alvar Road, Carden Alvar, Kawartha Lakes

Juvenal's Duskywing - Alvar Road, Carden Alvar, Kawartha Lakes

The remaining skippers that I identified were all either Hobomok or Arctic. Try as I might, I couldn't dig up any Two-spotted Skippers, and even European Skippers were not flying. Normally by now, thousands of them can be seen puddling on the road, competing with the native species.

Hobomok Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

Arctic Skipper - Alvar Road, Carden Alvar, Kawartha Lakes

Black Swallowtail - Alvar Road, Carden Alvar, Kawartha Lakes

For those worrying that I have stopped looking at birds altogether, fear not! I could not help but spend ten minutes watching a Black-billed Cuckoo furtively hunting in the roadside hedgerow. Eventually, it popped out onto an open branch for a few seconds - a rare occurrence with these birds.

Black-billed Cuckoo - Alvar Road, Carden Alvar, Kawartha Lakes

I will finish with a few more photographs of some of the other butterflies and moths from the afternoon. The Carden Alvar is an amazing place that I wish I could spend more time at!