by Glenn Coady
The return of the Peregrine Falcon (Falco peregrinus anatum) as a breeding bird in Ontario in both the northern and southern regions of the province in this decade has surely been a happy conservation success aided in no small part by a large-scale release program spanning nearly two decades. With additional nests being found in both the north and south each year the recovery is robust and has already met the recovery team's objectives.
I have listed below some milestones to be watched for in the ongoing spread of the Peregrine Falcon as a nesting bird throughout the province:
1) INFLUX = OUTFLOW
Simply put, since many of these birds are banded, we have been able to determine the origin of many of our mated pairs. Many of the birds from our breeding pairs originated from other jurisdictions (Ohio, Pennsylvania, Minnesota, etc.) and this is likely to continue since this bird is known to wander widely (hence the name "peregrinus") and it is also recovering in all adjacent jurisdictions as well. Now that our jurisdiction is producing significant numbers of fledged young we should soon be finding out that some of our Ontario young have moved to these other jurisdictions as well, until we reach a point where an equilibrium can be demonstrated whereby influx approximately equals outflow. This will help ensure a healthy gene flow in the population and should be possible to demonstrate with band recovery data and possibly satellite tracking methods.
2) Will the urban Peregrine Falcon spread to more natural
The first Peregrine Falcons to successfully nest in southern Ontario after an absence of several decades did so in 1995 at sites in both Hamilton and Toronto. By 1997 successful sites were present in Toronto, Hamilton, Etobicoke, London and Ottawa. There is every indication that additional sites are certain to add to this total this year. All of these urban birds so far are nesting on high-rise ledges in very urbanized settings.
This is in contrast to the northern Ontario experience in which wild cliff sites are being utilized. If these birds show pronounced fidelity for urban high rises it will serve to limit their spread through southern Ontario and thus it will be very interesting to see if any will make the move to more natural cliff sites in the region. It will be very interesting to see if they will utilize the Niagara Escarpment which would serve as a vector to spread them through many counties rapidly that don't offer the urban habitat they are currently utilizing. This transition will be pivotal to their reclaiming all their historical nesting territory in the province. Perhaps the excellent resource of the Bruce Trail Association could help document this spread when and if it occurs.
3) At what pace will additional nesting occur? How will we be
It will be interesting to see at what pace additional nesting will be documented and also whether it will outstrip our ability to detect and monitor it. I already believe there are nests going undetected in southern Ontario right now, and it would seem success in finding new cliff nests in northern Ontario so far has been proportional to the effort made to census likely cliff habitat. More simply put, will we find more nests simply by looking harder? The ongoing recovery may be fortuitously timed with the possibility of a second Ontario Breeding Bird Atlas to be undertaken soon.
4) North meets South
It will be exciting to watch and wait for contact between the northern Ontario cliff-nesters (as they spread south and east) with southern Ontario birds (as they spread north). Hopefully they will repopulate long abandoned Algonquin Provincial Park sites as well as other historical eyries they have been missing from for decades.
5) Adaptation to new habitats
It will be interesting to see if the Peregrine Falcon will use new habitats such as the many open pit quarries available across the province. Also, will we see any surprises such as adaptations to other kinds of nesting sites such as ground nesting (as described in Europe & Siberia) or tree-nesting (as described in the Baltic and Nordic regions and Australia).
6) At what point will monitoring efforts be superfluous?
Since the number of known nests is still manageable for the volunteers available, comprehensive monitoring efforts are undertaken at all known nests so far. This serves at least four compelling functions:
1) it dissuades Peregrine Falcon abductions (as likely happened at a failed nesting at Arnprior in the early 1980's);
2) it provides interpretive service to the general public;
3) it generates much anecdotal life history data; and most important to the recovery
4) it increases the productivity of each eyrie both by reducing fatalities at the crucial period of first flight as well as by providing opportunity to supplement captive-raised chicks into nests with low productivity (as occurred in Hamilton in 1995). It is hoped that the latter strategy will still be an option despite the closure of the captive breeding facility for Peregrine Falcons in Wainright, Alberta.
Like a chemical reaction that requires a certain activation energy and a catalyst to ensure the reaction reaches a certain equilibrium or endpoint, so too have monitoring efforts served as activator and catalyst to the Peregrine Falcon recovery in Ontario. However, at some point the lower productivity inevitable with the cessation of monitoring programs will no longer impede Peregrine recovery once they reach a certain critical mass. At what point will we know we have reached such a critical mass? How will we know for sure? Are we already there?
7) Size of the non-breeding population
At almost every nest being monitored in southern Ontario additional Peregrine Falcons beyond just the nesting pair have been attracted to the eyries on occasion. On one occasion at the downtown Toronto site four additional birds were seen simultaneously!
The size of this non-breeding pool of birds is critical and a good barometer of the robust recovery. It helps provide replacement birds at a site if one of the adults is killed or injured and it maximizes the chances that additional birds of opposite sex will meet, form pair bonds, and establish new nesting pairs. Thus monitoring of the non-breeding population is also useful to document to provide clues to where new eyries may occur.
8) Just how anatum is anatum?
In the last twenty years or so large-scale re-introduction efforts in the form of hacked releases of captive-bred Peregrine Falcons have been undertaken across a wide area of eastern North America in an effort to re-introduce the effectively decimated eastern population of the anatum subspecies of the Peregrine Falcon.
In Canada, all the birds released were pure anatum Peregrine Falcons provided by the captive breeding centre at Wainright, Alberta dedicated to this aim.
In the United States however, much of the sources of eggs & chicks for release programs were through a coordination of many private falconers and as such many of the birds provided were not pure anatum Peregrine Falcons but often were mixed with Peale's Peregrine Falcon among other subspecific mixes. This clearly was inconsistent with the aim of reintroducing pure anatum Peregrine Falcons and serves to this day to work at cross purposes with the Canadian goal.
As long as the proportion of pure anatum birds overwhelms the number of mixed race birds however the non-anatum genetic line will become much more dilute with time in much the same way as the Greater Prairie Chickens which became established in Ontario in the Manitoulin Island area in the early part of this century were hybridized out of the region by the early 1960's by the far more numerous Sharp-tailed Grouse.
It would be interesting to set up a way to monitor the change in genetic profile of this recovering Peregrine Falcon population with time.
Watching for, and learning from, many of these future Peregrine Falcon milestones should be very exciting in the years to come. The success and synergy of the cooperative efforts between public (Ministry of Natural Resources, Canadian Wildlife Federation, etc.), private (World Wildlife Fund, Canadian Peregrine Foundation and its sponsors, Wild Bird Clinic, etc.) and volunteer (Hamilton Naturalists, Toronto Ornithological Club, McIlwraith Field Naturalists, Ottawa Naturalists, etc.) organizations has been most gratifying to participate in. If you would like to be part of such an enjoyable effort please contact the Canadian Peregrine Foundation who I'm sure can direct you where your volunteer efforts will be rewarding for both you and the birds.
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