Prothonotary Warbler

Prothonotary Warbler

Tuesday, 7 February 2017

A CBC and a birding hotspot

Christmas Bird Count data is fun to examine.

On a local scale, the Blenheim/Rondeau CBC started in 1939, making the most recent count the 78th. I have been involved with this count since about 1969. I am not the compiler, but I have maintained the spreadsheet in the last few decades.

Over the first 20 years of the count, the number of species averaged 46. For the most recent 20 years of the count, the number of species averaged 107. Since the beginning, we have recorded 191 species, including a handful of birds counted during the official count week but missed on the actual count day.

Why so much difference?
-Are the birders that much better? Perhaps.....at least there are more resources available to help birders become much more proficient throughout the year, which likely translates into better identification.
-Are there more birders now, allowing greater coverage? It might be a factor, as the first 20 years for which the number of observers are given averaged 15 birders per count, whereas in the most recent 20 years, it has averaged 21 observers per count. However at the time I started on this count, and up until the last decade or so, participants were required to pay a fee in order to be listed as a participant, and I know that some people decided to forego having their name in the list of participants and did not pay, so likely there may have been a few more than the 15 participant average. In the most recent decade or so, no payment is required (although donations are appreciated) so every participant is accounted for.
-Are the optics that much better? There is no question that binoculars and 'scopes have improved immensely in the last 2-3 decades. No one uses the old standard, clunky 7 X 50 binoculars with low quality coating, or the standard Bushnell Spacemaster scope with a basic zoom that deteriorated quickly as soon as you started to zoom. They seemed great at the time, but fortunately the optics companies recognized the market potential for improved optics. The resulting competition amongst optical equipment providers has been a tremendous blessing to birders, with so many high quality binoculars and 'scopes available at decent prices.
-Is the habitat that much better? For many CBCs, it certainly is not better...quite the opposite, but in the case of this particular count, where Rondeau Provincial Park and Rondeau Bay is a cornerstone of the natural habitat, there hasn't been a lot of change.
-Has the weather changed? This might be one of the most significant factors. The mild autumns in the last couple of decades or so, resulting in the delay of winter's arrival likely causes more birds to take their chances and linger longer. Whether they survive or not is another question.

Red-throated Loon
Related to the delay of winter, is the increased amount of open water available for waterbirds. Waterbird diversity and numbers have gone up considerably in the last few decades. In addition, the arrival of invasive species such as Zebra Mussels, has caused tens of thousands of diving ducks to remain on Lake Erie longer than they used to. For example, during the first 20 years of this count, there was an average of 5 Greater/Lesser Scaup observed per count. In the last 20 years, we have recorded an average of 11174 Greater/Lesser Scaup, with an all-time high of 56019 observed in 2001!
Greater Scaup

Regardless of the actual factors, but likely a combination of those just listed, bird numbers are better than ever, in terms of species diversity. It wasn't that long ago when we thought tallying 90 species was the benchmark for a successful count. The first year we achieved that was in 1971, when we tallied 94 species. It wasn't until 1994 when we hit the magical 100 species mark. Since 2000, we have tallied less than 100 species on only two occasions. In the most recent decade, we have hit 115 species on two occasions.

With so many years of data, there are some interesting observations. (Note: of the photos that follow, only a couple were actually taken during the count.....most of the time, counters are too busy!)

The species holding the highest record the longest goes to Northern Bobwhite, when an amazing 89 were tallied back in 1944. Of course this species is now endangered in Ontario. They are so rare, that I don't even have a photo of one taken in Ontario. This next photo was taken during one of my visits to southwestern Missouri, where the tallgrass prairies are still relatively abundant across the landscape, and the Northern Bobwhite population is reasonably healthy.

Its numbers had been dwindling steadily in Ontario for several decades. They were tallied fairly regularly for the first few decades of this CBC, albeit in declining numbers, up until 1977. It was the the combination of severe weather in southwestern Ontario for three successive years: a major ice storm of March, 1976, along with the blizzards of late January in both 1977 and 1978 that finished them off. They have only been recorded once since 1977, and those four birds noted in 1988 were likely the result of an attempt at re-introduction.

Another 'oldest record' is that of Ring-necked Pheasant, when 17 were recorded in 1950. They have been recorded since then, but 1950 still has the record, and likely will for some time to come.


As one might expect, there have been some amazing numbers of some species in various years. For example there were:
-625 White-winged Scoter observed in 2014
-15300 Red-breasted Merganser in 2011
-627 Ruddy Duck in 2014
-53 Pied-billed Grebe in 2001
-75 Northern Harrier in 1973
-74 American Kestrel in 1999
-8202 American Coot in 2001
-32 Wilson's Snipe in 1998
-26 Snowy Owl in 2014


-44 Winter Wren in 1983
-55 Carolina Wren in 2006
-6 Northern Mockingbird in 2004
-4 Little Gull on more than one occasion, most recently in 2007
-30 Eastern Towhee in 1960
-540 Swamp Sparrow in 1976
-17132 Snow Bunting in 2004
-137 Eastern Meadowlark in 1974. It is currently a legally Threatened species in Ontario.
-575 Rusty Blackbird in 1976. It was being considered a Species At Risk fairly recently, but so far has not quite made the list.
-1037 House Finch in 1992. It only arrived in Ontario in the late 1970s and the population exploded for a few years but has declined to a more realistic number in the last couple of decades. We've averaged a mere 229 over the last decade.

There have been some unusual sightings, as well. We've had 14 species of shorebird, most notably American Avocet, Black-bellied Plover, Lesser Yellowlegs, Spotted Sandpiper (twice),Western Sandpiper and Red Phalarope.


There have been 12 species of gull, including 12510 Ring-billed in 2001.

There have been 9 species of woodpecker including both Black-backed and American Three-toed. A Brant was recorded in 1968, and a Tufted Duck in 1983. There were 3 Virginia Rail in 1986 and a Spotted Towhee in 1990. There have been 7 species of warbler and a Sage Thrasher in 2008.
Sage Thrasher of 1981 on the Marsh Trail
Each count is different, depending on the autumn and early winter weather leading up to the count, and of course the weather of the day. I've been canoeing in the open marsh some years, and some years there have been very high winds and blizzard conditions making even getting around difficult let alone counting birds. We have only had to reschedule one count due to weather so far, back in 2007.

It is clear that the Rondeau/Blenheim/Erieau area is a hotspot for birds, and birders, even in winter!

















2 comments:

  1. I used a Bushnell Spacemaster when I started out. I picked it up a Canadian Tire for thirty bucks. I think I like my Vortex one better though :)

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    1. The Bushnell Spacemaster was likely the 'scope most commonly used at one point, and they were decent enough at the time. Fortunately there are so many better options available now, including Vortex.

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