For the third winter in a row a peculiar Canada Goose (Branta canadensis) has put in an appearance at Chaffey’s Lock. I first saw this uniquely patterned goose (see picture) over a number of weeks at Chaffey’s Lock in the winter of 2008-09. I subsequently found it paired with a normal-plumaged Canada Goose on a beaver pond in the remote northeast corner of the Massassauga Tract where it was present with its mate and a brood of four goslings in May 2009. In the winter of 2009-2010 I saw it only once at Chaffey’s Lock. The bird was again present among 26 other Canada Geese on December 16, 2010.
Aberrant plumage such as in this goose, can be the result of many factors including hybridization, leucisim, albinism, malnutrition and injury. But it can be difficult to say confidently what the cause of strange colouration in individual birds is without close examination in the hand. Although Canada Geese will hybridize with Snow Geese (Chen caerulescens) to produce offspring that have dark and light patches of plumage, this particular bird doesn’t match the typical hybrid plumage or bill shape very well. That this bird sports the same odd plumage each year suggests that it’s not the result of malnutrition or an injury to growing feathers. Perhaps this goose is either partially leucistic or partially albino. Lecucisim is when a bird lacks black pigment in its feathers. Albinism is when a bird lacks all colouration in the feathers and other tissues. Without a closer look at this goose it is hard to say which of the two it might be, but the pink bill and snow-white feathers suggest a partial albino. A more typical appearance for a leucistic Canada Goose is to have feathers that are not so white but instead are a washed-out brown.
Although colour variations such as albinism are not extremely rare in Canada Geese, this bird is an interesting one because its distinctive plumage means that it is possible to glean some information about the life history of a single bird, even if it is only in glimpses from time to time.
The Cerulean Warbler (Dendroica cerulea) is emblematic of QUBS and the southern Frontenac Arch. It has been the subject of research at the biological station since the 1990’s and indeed much of the basic natural history knowledge biologists have about this canopy-dwelling bird is the result of field work done right here at QUBS. In addition, hundreds of birders flock to Opincion Road and the area around Frontenac Provincial Park every spring to tick this species off their checklists. Cerulean Warblers are therefore a big deal to those of us who live, work and play in this part of the Arch. It’s therefore worth noting that Cerulean Warblers are now classified as endangered in Canada.
The Committee on the Status of Endangered Wildlife in Canada (COSEWIC) is the governmental body that assesses the conservation status of species in Canada and recommends them for protection under federal species at risk legislation. In November COSEWIC reassessed the status of Cerulean Warbler and upgraded it from a species of special concern to an endangered species. The previous designation (special concern) was conferred in 1993 and reassessed as such in 2003. A species of special concern is one that has not yet become so severely imperiled as to be considered threatened (yet another official level of classification) or endangered but could become so if certain risk factors are not mitigated. Classification as endangered is far more serious and means a species is “facing imminent extirpation or extinction” in Canada (see COSEWIC). There are a number of factors that make extirpation a realistic possibility for Cerulean Warblers. Logging, forest degradation and fragmentation in the wintering habitat (the South American Andes), the apparent rarity of suitable breeding habit in Canada, and continued rapid population decline throughout much of its range since the 1960’s are all cause for grave concern.
COSEWIC reports that there are an estimated 1000 Cerulean Warblers breeding in Canada annually. Intensive field work in May and June this year estimated about 100 breeding pairs (200 individuals) at QUBS. If those estimations are correct then lands owned by the biological station are home to 20% of Canada’s Cerulean Warbler population. The importance of our mature forest tracts which, Cerulean Warblers use for breeding cannot be overstated.
Cerulean Warblers are now classified as endangered on a national scale but still only as special concern provincially; even though nearly the entire Canadian population of Cerulean Warblers breeds in Ontario. However, reassessments of species at risk are ongoing at the provincial level so their classification may or (may not) come into line with the federal list. For an explanation of how the federal and provincial species at risk lists differ click | here |.
In recent years a great deal of attention has been paid to monitoring phenological changes in organisms and annual events such as ice cycles on lakes. Longterm datasets are an invaluable resource for studying changes over time, especially in the face of rapidly rising global temperatures and associated climate change. Frank Phelan and Floyd Connor [Manager and Assistant Manager (until Feb. 2010) respectively] have kept track of the date of freeze-up and thaw of ice on Lake Opinicon since 1985. Here we summarize this data (Table 1). Lake Opinicon is located on the Rideau Canal system in the Cataraqui-Gananoque Watershed. QUBS sits on the northwest shore of this lake. The lake has an area of 788 ha with approximately 61 km of shoreline (including islands). The mean depth is 2.8 m and the maximum measured depth is 11.3 m. Researchers use Opinicon extensively for studies of a variety of taxa including water mites, odonates, fish, turtles and plants, therefore making an understanding of lake ice phenology very important. Furthermore, changes in date of freeze-up and thaw can act as a proxy for monitoring climate change (Magnuson et al 2000; Futter 2003).
For our purposes the date of freeze-up means the day on which no more open water is found on Lake Opinicon. This is the formation of permanent ice with no patches of open water subsequently forming until the thaw. It is important to note that there is almost always some open water on Lake Opinicon where strong currents from in- and outflows preclude ice formation (i.e. Chaffey’s Lock, Davis Lock and Deadlock Bay) so complete freeze-up refers to all but these small areas. The earliest complete freeze-up on record (22 years) was on 24 November 1995. The latest was 1 January 2007 (for the winter of 2006-07) (Figure 1). The median day of freeze up is 9 December. We are missing records for the years 1987, 1991 and 2002 and at the time of this blog post Lake Opinicon had not frozen for 2010 (there was skim ice between Rabbit Island and Cow Island on November 6 and skim ice from shore to shore on November 23 that was later broken up by wind and waves. Some of the back bays have been frozen for a few days at a time but that ice is still ephemeral).
Date of thaw is the day on which generally no more ice is present on Lake Opinicon. At this date there is certainly no more fast ice (ice attached to shore) but a few small floating pieces may still be present, however in general there is no more ice left on the lake. The earliest complete thaw (26 years) was 26 March 2000. The latest was 23 April 1992 (Figure 2). The median day of thaw is 12 April.
The longest duration of winter ice cover (22 years) was 143 days in the winter of 1995-96. The shortest was 97 days in the winter of 1999-2000 (Figure 3). The mean duration of ice cover on Lake Opinicon is 119 days. We could not calculate the duration of ice cover for the winters of 1987-88, 1991-92 and 2002-03 because of unknown dates of freeze-up.
Though some other Ontario lakes have shown a trend toward a longer ice-free season since the 1970’s (Futter 2003) there is no such trend apparent in the QUBS data. Clearly there is dramatic year to year variability in the timing of freeze-up and thaw events at Lake Opinicon. It
will likely take several more years before any trend that could be indicative of longterm climate change becomes evident.
Futter, M.N. 2003. Patterns and trends in Southern Ontario lake ice phenology. Environmental Monitoring and Assessment 88: 431-444.
Magnuson, J.J., Robertson, D.M., Benson, B.J.,Wynne, R.H., Livingstone, D.M., Arai, T., Assel, R.A., Barry, R.G., Card, V., Kuusisto, E., Granin, N.G., Prowse, T.D., Stewart, K.M. and Vuglinski, V.S. 2000. Historical trends in lake and river ice cover in the northern hemisphere. Science 289: 1743–1746.