Friday, June 24, 2011

A Great Day for Emergence at Camas Prairie

I just returned from a visit to Camas Prairie, Oregon, which is a little ways south of Mt. Hood in the Cascade Mountains. The prairie is a large wet meadow and great for a lot of montane odonates in the Pacific Northwest. Because of the late spring-like (cool and wet) conditions in the region, I didn’t expect much activity at Camas Prairie, but emergence of several species is well underway.


View Larger Map


There were lots of adults of four species: of the dragonflies, Four-spotted Skimmer (Libellula quadrimaculata) and Hudsonian Whiteface (Leucorrhinia hudsonica); of the damselflies, Western Forktail (Ischnura perparva) and Western Red Damsel (Amphiagrion abbreviatum). The skimmer and whiteface were emerging in large numbers as well...

A female Four-spotted Skimmer emerging. Note the exuvia (shed nymphal skin) at the base of the sedge stem.
An emerging female Hudsonian Whiteface still holding on to its exuvia. Another one is in the background to the left.


I never saw any darners flying around, but obviously many have emerged recently as indicated by the numerous exuviae in the water. Several Canada Darners (Aeshna canadensis) were in the process of emerging. That species is one of the earlier of the montane darners to make an appearance and I assume most of the abandoned darner exuviae belong to them...

On left, two darner exuviae are floating on the water surface. On right a female Canada Darner is almost done emerging.


I was surprised to find a Subarctic Darner (Aeshna subarctica) emerging. Within Oregon, this species is known from only a few sites in the Cascades south of Mt. Hood, but it is most abundant at Camas Prairie. The earliest known flight date for the species in Oregon was 27 July, however, so this is more than a month earlier.

An emerging male Subarctic Darner clinging to its exuvia.


Another surprise was an emerging Brush-tipped Emerald (Somatochlora walshii) which beat the previous earliest flight date of 6 July in Oregon.

On left, an emerging male Brush-tipped Emerald clinging to its exuvia. The same individual on the right after it was carefully relocated in order to collect the exuvia. You can just make out the "brushes" on the tip of the abdomen.

6 comments:

  1. Great photos! All those emerging dragonflies must have made an awsome day!

    ReplyDelete
  2. Cool photos, Jim. Believe it or not, I am thinking about exploring Camas Prairie this weekend. I've heard about this place for years, since back when I was doing some genetic research on the Oregon spotted frog population there. But I've never actually set foot on the prairie.

    Should I take waders if I go? Were the mosquitos terrible?

    ReplyDelete
  3. @Ivan Phillipsen Thanks, Ivan. Camas Prairie is a very wet meadow, so if you typically use waders you'll want them along. I normally don't bother with waders, but that's me. I do find a lot of leeches when I dig for nymphs there, but I've never found one enjoying a meal on me there.

    The mosquitoes can be annoying in the woods and at the end of the day, but not typically out in the meadow during the middle of the day. Have fun!

    ReplyDelete
  4. I am part of a group that does amphibian and crane surveys at this site throughout the spring and summer. If you go to the prairie, be careful of the spotted frog tadpoles that are just metamorphosing – this increasingly rare species is finally making a come-back at this meadow and we don’t want to trample any of the tadpoles or emerging young frogs. Also, be careful not to get too close to the cranes – they may have colts (this year’s fledglings) nearby that may spook or get injured if people get too close!

    ReplyDelete
  5. @Laura Guderyahn Thanks for the warning, Laura. I would add that odonates are very fragile during and right after emergence, and they are not likely to recover if they are knocked into water. Visitors should be on the lookout for them in the vegetation and avoid contact as much as possible.

    ReplyDelete