FEATURES - FALL 1996
ALBERTA'S WATERFOWL REBOUND
By Tom Sadler
There is a great deal of excitement shared by waterfowl biologists and avid birders who have visited a marsh this summer. For the first time since the mid1970s, spring water was abundant throughout the entire breadth of North America's duck factory from Alberta to Manitoba, as well as the pothole country in the Dakotas.
During the dog days of summer, the marshes were teeming with young waterfowl. The visionary waterfowl biologist Johnny Lynch believed this region which he called the Bald Open Prairie (BOP), was the key to the production of a "super crop" of ducks.
"Let good fall rains soak the soil, and heavy winter snows melt quickly in the spring so snow water runs into the sloughs instead of into the ground, and the BOP is ready to raise ducks," Lynch wrote. "Add liberal spring and summer rains, and these fowl multiply like bacteria."
Well, maybe not quite like bacteria, but it is a good year and the best we have seen in a very long time. The spring waterfowl breeding population surveys for the southern half of Alberta have reached a total breeding population estimate of 3,890,900 this year, an 18 per cent increase from 1995. Ducks are doing better than they have on average in the last 10 years.It is important to remember however that the current 10year mean period (19861995) has been characterized by decreasing waterfowl populations and habitat conditions. Duck populations in the region are still 15 per cent lower than the longterm mean (19551995), a period that included the wet and bountiful 1950s.
Pintail Nmbers Up
The mallard population registered a modest increase of two per cent from 1995 (down 32.3 per cent from the longterm mean). The good news is that the greyhound of the skies, the northern pintail, showed a significant population increase of 68.3 per cent over last year. Pintail numbers are 25 per cent above the recent 10year mean, although still remaining 60 per cent below the longterm mean. The numbers represent an 84 per cent drop from 1974 when the pintail was the most numerous waterfowl species in this region.
Though the final numbers for the year have not yet been tallied, Karla Guyn, a PhD student, who is in the third year of her pintail study near Brooks, Alberta, reports that this is the best of the three years by far. The pintail has had good nest success particularly early in the season, and good brood survival.
For this year at least the trend for the pintail is positive and some other species have also shown substantial increases including the bluewinged teal, American greenwinged teal, and northern shoveler.
Pine Lake Report
At the mallard research site at Pine Lake in central Alberta, the hatch was poor early in the season but improved substantially later in the summer. This site was heavily grazed in 1995 with resultant poor nest cover in the spring of 1996, but there has been a significant improvement in the nest cover there. The hatch at the Pine Lake area was the latest to date in the assessment studies, but Doug Shaw reports that a much stronger nesting effort has been noticed this year, likely due to wetland conditions and weather. There has been high predation at this site this year and raptors appear to be the major culprits.
Bluewinged teal also did well according to observations in the Pine Lake area.
Alberta's Peace River parklands have only been surveyed for the past seven years, but waterfowl populations there are generally much more stable due to a more dependable water supply. Conditions there are also good in 1996 and the breeding duck population index increased 15.8 per cent from 1995 to a total of 1,609,400 ducks, the highest count since records started in 1989.
In the boreal forest region of northeastern British Columbia, northern Alberta and the Northwest Territories, all duck numbers were down despite an increase in the habitat quality since 1995. Although this may in part be due to a very late spring, it is undoubtedly a reflection also of the very good conditions further south in what is the preferred breeding range of the ducks when habitat conditions are suitable.
Canada goose populations continue an upward trend in central and southern Alberta while still remaining relatively stable in the north. The southern Alberta breeding population now stands at 160,200 in an area which contained virtually none when these waterfowl surveys began in 1955.
Overall, the picture is very good and we can expect an increased fall flight in 1996. The numbers are so good that a recent visitor from California, who had toured some of our southern Alberta habitat, remarked that "this would be a good year to buy another duck club." A good year indeed.
Like the populations of many other creatures, waterfowl numbers have ebbed and flowed with the boom or bust drought cycles of the prairies and parklands. In recent decades waterfowl numbers reached their highest levels in the wet years of the 1950s followed by a decline during the 1960s. A return to wetter conditions in the 1970s produced a secondary peak but this was followed by a steady decline throughout the 1980s to alltime low levels by the end of that decade. A slow recovery began with the 1990s and this year should add impetus to that growth.
The Agriculture Factor
During the past 25 years, it has become evident that waterfowl numbers are no longer determined solely by the annual spring water conditions. Other factors have come into play. These factors relate to changing agricultural practices and the intensification of agriculture. Populations of some waterfowl species, most notably the pintail, have remained below levels predicted solely by variation in the wetland conditions.
This difference in numbers, between what was expected under those water conditions and what was happening in reality, correlates with the magnitude of recent expansion of rowcrop agriculture. This homogenization of the prairie landscape has hampered the reproductive success of waterfowl and has slowed the rate of recovery which is below normal expectations for the water conditions.
Changes in agricultural equipment and farming practices coupled with the prolonged drought of the 1980s resulted in the nesting success of waterfowl dropping to levels too low to sustain the population levels. The widespread use of large tillage equipment has resulted in the removal of fence rows and small cover areas. At the same time this equipment, in combination with the prolonged drought conditions, allowed farmers to cultivate wetland margins and to till directly into dry wetland basins. Upland nest cover was further impacted by an increased livestock herd on pasture lands already affected by the drought conditions. Poor nesting cover in turn made the nesting waterfowl more susceptible to predation and nesting success rates dropped to alarmingly low levels.
In order to address these low nesting success levels, Ducks Unlimited in conjunction with the North American Waterfowl Management Plan (NAWMP) partners, has introduced the Prairie Care program aimed at restoring the balance between upland nest cover and wetland areas. The program also encourages farming practices in harmony with a healthy wetland environment. Studies are ongoing as to the success of this program but some of the early returns are in, and nesting success has been much improved in many areas. This improvement has been further augmented by the return to wetter conditions which have in general improved the overall condition of rangelands and flooded small wetland basins and wet meadows, preventing the cultivation of these areas. Nesting success remains a concern in many areas, as low success rates are still evident despite the much improved habitat conditions.
In a study (supported by Ducks Unlimited Canada, the Institute for Wetlands and Waterfowl Research, and the Alberta NAWMP Centre) recently concluded in the aspen parkland of central Alberta, the nesting success of female ducks in hay fields was found to be very low. There was also a significant direct loss of female ducks nesting in the cover. Hay fields provide attractive cover for uplandnesting waterfowl but field suitability varies for early and latenesting ducks. In most hay fields which are cut twice a year, there is little residual cover the following spring to attract the early nesting waterfowl. By late May there has been significant regrowth and hay vegetation becomes highly attractive to the latenesting waterfowl. High attractiveness of hay fields, however, does not necessarily result in high nesting success. Most female ducks nesting in hay do not complete their incubation before the first cut and are vulnerable to mortality during hay mowing.
There is hope of reducing this type of waterfowl mortality. In this study, the test of a tractormounted flushing device was shown to reduce female duck mortality regardless of the type of mower. While such flushing devices may save the hens during hay mowing, they do little to increase duck recruitment from hay fields because few nests hatch after mowing occurs. Birds flushed do however have the opportunity of nesting again, and there are other methods of reducing nesting loss. Alternative solutions to mowing hay during the nesting season presently offered or promoted by the NAWMP include:
- Annual payments to delay haying until after July 15 growing forage crops that are inherently harvested after midJuly such as densified timothy and forage seed operations.
- Experimentation with late maturing varieties of forage.
In cold wet springs such as we have experienced in much of Alberta in 1996, haying operations may be naturally delayed and this could significantly reduce nesting mortality.
We have had a strong late hatch in 1996 which should result in significantly improved recruitment to our waterfowl populations. Heavy rains in the Alberta parkland this summer have actually resulted in improved wetland conditions over spring levels, and we should see good wetland carryover into 1997. If this can be augmented with good winter snows and spring runoff in 1997 in the prairie region, the present recovery in waterfowl populations can be expected to continue, and the future for our waterfowl looks bright. For those duck hunters on the wintering grounds of our waterfowl, 1996 might indeed be "a good year to buy another duck club."