Red Admiral Butterflies stream through Ontario

Nature Notes for April 27, 2012

Red Admiral butterfly                          ©Bruce Parker

As I write, the temperature is only a couple of degrees above freezing, there is a strong wind and the weather forecast is for a mix of rain and snow. It’s hard to believe that the most recent flurry of excitement among naturalists concerned butterflies.

The first reports were from southwestern Ontario on April 15. Several hawk watches reported massive flights of Red Admiral butterflies. By Monday, April 16, they were in Northumberland. They were being reported in Ottawa by the end of the week. By Saturday, April 21, even the Toronto Star had noticed.

Those who study butterflies were amazed by the sheer numbers. Most were declaring that they had never seen such a flight.

Red Admirals are about two-thirds the size of a Monarch, medium sized by butterfly standards. They are quite easy to identify. The upper side is mostly black, with an orange band in the middle of the fore wing and another orange band on the trailing edge of the hind wing. The tip of the fore wing also has several white spots.

They are one of the butterfly species which overwinter as adults. They don’t usually survive Ontario’s winters. They overwinter in the southern states or Mexico and migrate north when warm weather arrives.

Red Admirals are a Holarctic species, that is, they occur in Europe and northern Asia as well as in the Americas. The occur all across Canada and have been recorded as far north as the Yukon and Northwest Territories.

The adults feed on flower nectar. Last week, there were several reports from around Port Hope of flowering trees or shrubs covered with dozens of butterflies.

In my garden, there were not many flowers in bloom: a few scilla, pulmonaria, the first violets, hyacinths and daffodils. The latter two are probably too large for the butterflies to use. In any case, the Red Admirals I observed in my garden didn’t stay for long. They paused briefly to sip at a flower and then continued flying north.

The caterpillar, or larva, feed on stinging nettles as well as several other species of nettle. I haven’t yet seen much growth of nettles so the female Red Admirals have no place to lay their eggs at present. The Red Admiral caterpillar is usually black with white dashes along its sides and tufts of bristles.

The caterpillar lives in a rolled leaf nest that it makes on the food plant. I wasn’t able to find any indication in my reference books as to whether many birds eat these caterpillars. Many birds find fuzzy caterpillars unappetizing.

Migration is a risky undertaking. This huge flight of Red Admirals came very early, with warmer than average temperatures and brisk south-west winds. Although this flight was mostly of Red Admirals, a few Question Marks and American Ladies, two other migratory butterfly species, could be found in the flight.

Then early this week, the weather changed: cold, rain and snow in areas north of Northumberland. Many of these butterflies will probably die if the cold persists for several days.

A word of caution to readers who check out this butterfly on Google. Only two of the five photos shown are actually of Red Admirals.

Eastern Bluebirds thrive on Rice Lake Plains

Nature Notes for April 13, 2012

Eastern Bluebirds are truly beautiful birds and we are lucky enough to live in an area where they can be easily seen. The Rice Lake Plains, just south of Rice Lake, are home to a healthy population of this species.

The male of this small thrush is bright blue on the back, with a brick red breast the same colour as a robin’s breast, and white belly. The female is a faded version of the male. They have a gently warbling song.

Bluebirds prefer open habitat with scattered trees. The trees must contain dead snags with old woodpecker holes in them for nesting. They feed on arthropods in the breeding season. They feed their young on insects as the nestlings require animal protein to thrive. Their preferred hunting technique is to sit on a perch to search an area of short vegetation and then drop to the ground to capture their prey.

Before European settlement in Ontario, they probably occurred on the Rice Lake Plains, the savannah around Lake St. Clair and in areas that had been subjected to forest fires. The rest of the province was covered by dense forest which was not attractive to this species.

In winter they form small flocks and feed mostly on fruit. In a winter such as has just passed, many bluebirds remained in this area throughout the winter. The winter was relatively mild, with little snow and an abundance of fruit, some of which is still hanging on vines and bushes.

Bluebirds are secondary cavity nesters. That is, they nest in cavities in trees excavated by other species, mainly woodpeckers. In the mid-twentieth century, their population was in such a decline that they were listed as threatened. There were a number of reason for this decline, but chief among was the competition for nest cavities from two non-native species, the European Starling and the House Sparrow.

Fortunately bluebirds will nest readily in human built structures. Founded in 1978 by Dr. Lawrence Zeleny, the North American BluebirdSociety encouraged people to erect nest boxes in suitable habitat. NABS provided information about bluebirds and their needs and recommended nest box plans for those who wanted to help.

If nest boxes are built with the correct size opening, they will exclude European Starlings. However, a nest box that will admit a bluebird will also admit a House Sparrow, so care must be taken to site nest boxes away from areas that have House Sparrows.

Male bluebirds will vigorously defend their chosen nesting cavity from all competitors. I was recently told of a male who successfully defended  his nest box from a starling. He attacked the starling and pinned him to the ground and sat on him for about ten minutes.

Two other native bird species will also compete for these artificial cavities, the Tree Swallow and the House Wren. Since Tree Swallows are semi-colonial in their breeding habits, spacing the boxes 200-300 meters apart will make them less attractive to Tree Swallows. To deter House Wrens, the boxes should not be placed near shrubby habitats or wood edges.

In this area, Hazel Bird started a nest box trail in the Harwood area which she maintained for over 30 years. Due to her efforts, bluebird populations have recovered in this area.

There are two other species of bluebirds, Western and Mountain. The Western Bluebird doesn’t seem to wander outside its stronghold in western North American. The Mountain Bluebird on the other hand, sometimes wanders east. One was found this past winter in Prince Edward County and was seen by quite a few birders.

For more information about bluebirds, refer to the web site of the Ontario Eastern Bluebird Society, oebs.ca or the North American Bluebird Society, nabluebirdsociety.org.