The common nighthawk (Chordeiles minor) and
chimney swift (Chaetura pelagica) - local seasonal appearance
Based on the timing of 87 observations of two summer residents in Seymour township,
Northumberland county, southeast Ontario, 1999-2004.
The earliest and latest sightings in this six-year period were 13 May
to 25 August (nighthawk) and 11 May to 07 August (chimney swift).
24 sightings were noted for the nighthawk (lower data set on the plot),
declining gradually from May
to August, plus 63 sightings or sound-recognitions
of chimney swifts, with clear peaks in May and
July (upon return and prior to departure), based on all available data.
No nighthawks were heard or seen in the area during 2003,
and only one in 2004, on 13th May - this is
disturbing, as the birds have seemed like a seasonal clock over the
past 20 years, typically appearing along the Lake Ontario
shore and downtown Toronto around May 20th each year.
A report on birds at Presqu'ile for Saturday 30 August 2003
noted the sighting of six nighthawks over the marsh,
a park record for the year to that date.
The typical migration times of these birds through Presqu'ile
provincial park, located roughly
40 km south of the town on the north shore
of Lake Ontario, is around mid-May and mid-September (nighthawk)
and late April and early October (chimney swift:
LaForest, 1993, pp.218,221).
In 2022, I intend to update the local status of 4 summer residents, all
insect-eating species: the nighthawk,
chimney swift, barn swallow and tree swallow.
Since these notes were first written, close to 20 years ago, these
birds have seen a drastic decline in our region.
While there may be local holdouts for some, e.g., farmyard barns
for swallows, it appears that the nighthawk and possibly the chimney swift are
all but extirpated from our area. Reasons are diverse, but decline
in the populations of flying insects is surely the key factor.
Shortages of acceptable nest sites for each species
(hollow trees, gravel roofing, chimneys...) may be another explanation.
I never thought I would worry about the vanishing of mosquitoes and blackflies!
Global warming may be another force in play here: in this case, possibly the birds
now nest further to the north, in which case the locally-dire viewpoint may indicate
extirpation rather than extinction.
Bird expert Pete Dunne (2022)
described a short (1 or 2 mugs- of- coffee length) observing period
on the Delaware Bayshore,
in southwestern New Jersey, some 600 km S.S.E. of Trent Hills.
The observations were made one mid-August morning, almost certainly
(though not explicitly stated) in 2021.
The salt marshes on the east side of Delaware Bay run north from the famed birding hot-spot of
Assorted swallow species, and a huge transient population of purple martins
occur here, along with many ospreys, and other birds.
Dunne also notes
"chimney swifts, as omnipresent as crickets this time of year. On trembling wings, scores of swifts cut cookie-cutter patterns
over our town, feasting on the insect riches of the Bayshore".
That's a relief: swifts seem to be doing well in other places, even though our local
population has plummeted.
Leslie Anthony (2020), writing in Canadian Geographic, reviews
Humanity's variable (determined to stumbling to non-existent) efforts at stabilizing biodiversity.
Buried in his good review are some worthy morsels, food for thought. Here are just two of these:
Updates on these and other species are intended for 2022.
- Bridget Stutchbury (York University) is quoted as estimating the cost of improving the status of one endangered bird species at 1 million dollars a year and
that, by extension, "if every taxpayer in North America gave $10 each year,
we could probably save everything (in North America)" (ibid., p.63).
Collectively, we have the money. No doubt - because habitat degradation is a key
driver of biodiversity loss - in many cases the actions taken to help one
species would help many others, at no extra cost.
- The second point is especially relevant to attempts at documenting
regional biodiversity, such as the natural history listings and species profiles on this web site.
Anthony cites fisheries scientist
Daniel Pauly (University of British Columbia)
as identifying, in 1995, a phenomenon known as shifting baseline syndrome
(ibid., p.66). This refers to a tendency to overlook the past. In our case,
every generation of scientist- naturalists reviews their chosen field as their careers
progress, and inevitably looks back 10, 20, 40 or more years, to the conditions that applied
when they began. But factors such as, say, the number of nighthawks seen in one area
in a summer, will have varied for millennia, and certainly back to a time when human activity
had essentially zero impact on most wildlife populations.
At the very least, we need to seek the advice of our elders,
while they are still with us, and to hunt the relevant literature
for clues to past conditions.
Anthony,L (2020) The sixth extinction. Canadian Geographic 140 no.5, 58-67, September.
Dunne,P (2022) Got to make the morning last. Birdwatching 36 no.1, 14-15, January.
LaForest,SM (1993) Birds of Presqu'ile Provincial Park.
Friends of Presqu'ile Park / Ontario Ministry of Natural Resources,
Graham Wilson, posted 20 May 2003, updated 08 July 2005, 15 January 2022, 06 February 2022
Township Bird List