Bison Birds

The American Bison was historically called buffalo. That is a misnomer, as buffalo are actually old world species, but when European explorers first arrived to North America and encountered these huge animals, they named them something that they were familiar with.

 Bison once roamed in the millions, mostly across the wide open plains of middle and western North America. There is some historical record of them even in extreme southwestern Ontario, in the vicinity of what is now the Windsor area, as there were hundreds of hectares of tallgrass prairie before settlement. But that is the topic for another post.

Bison were well adapted to the cold, fierce winters of the mid-western part of the continent. Their winter coats were densely hairy, as this image shows, with the front end of the animal being the most densely hairy.

This was incredibly useful when facing the wind, which they typically did, to withstand the cold.

After the winter weather, they lost much of the dense hair towards the back of their bodies as shown next. Even so, the front end of the animal still retained a lot of dense hair. 

 Bison were always known to roam widely. The huge herds would have a home range of hundreds of thousands of square kilometres or more of open grassland. This next photo shows a single bull bison on a huge grassland at Grasslands National Park in extreme southern Saskatchewan. At the time I took this photo, in July, the bulls are usually well away from the cows and calves.

 It was said by early explorers that bison always moved into the wind as they were foraging, especially during the more inclement weather. This resulted in their long-range movements, and was advantageous in that a large herd of bison, numbering in the thousands, would eat off much of the short-grass prairie, but by keeping on the move, they would find new grasslands and give the areas they moved from, a chance to regenerate in time for a following season. Sometimes they would feed intensively on areas that had burned off via a prairie fire, and was regenerating with lots of tender fresh, green fodder.

Tallgrass Prairie National Preserve, OK

And that brings us to the Bison bird.

Most birds build their own nest, lay their eggs in it and raise their young.  This next photo shows a typical eastern grassland type bird nest. It is that of a Song Sparrow, and at the time of taking this photograph, it did not have a cowbird egg in it.

 But the Bison bird is a species that depends on following Bison, for the insects they disturb by their hooves during their movements as well as the seeds they break off of the grasses they are moving through. So the birds must follow the movements of these herds of Bison, and don't stay in one place for several weeks while they build a nest, lay eggs and feed the young to the point of the next generation being able to fend for themselves. No, these Bison Birds adapted so as to lay their eggs in the nests of other birds, with the new host raising the young of the Bison bird.

As time went on, Bison herds diminished considerably, and were at great risk due to the loss of foraging and roaming habitat due to settlement as well as the slaughter of millions of animals for their hides, or just for what was considered 'sport'. Large areas of the Bison's former habitat was turned into grazing lands for other animals, such as beef cattle. Probably the most best known breed at one point was the Texas Longhorn, but other breeds were eventually added. Hence the likely reason for the current name of this bird species. Texas Longhorns were aptly named, and came in various colours. They were the new grazer of the mid-western part of North America, some roaming free and others on large fenced grazing lands.

I'm sure that most readers will have caught on quite early in this post that the bird species I am referring to is none other than the Brown-headed Cowbird. 

male

female

 It is the only North American bird species that demonstrates this 'parasitic' behaviour, much to the dismay of some bird enthusiasts. I admit that I have had mixed feelings over the years, especially when I see a cowbird egg in the nest of a more 'desirable' species such as a Yellow Warbler, Prothontary Warbler, Wood Thrush, or some other species. All three of the aforementioned species have been, or are, considered a Species At Risk. 

Yellow Warbler

Not quite sure if this next image showing the young bird being fed is a cowbird or a young Yellow Warbler. It has some characteristics of being a cowbird, but would be easier to tell a few days after this photo was taken.

  Cowbirds are certainly not at any level of risk. In fact they often can be seen in huge flocks.

 

Presumably when these Bison birds were more or less confined to the wide open spaces of the mid-west, they had fewer potential host species to choose from. But as the eastern forests were cut down and opened up to a more agricultural landscape, these Bison birds adapted and became widespread throughout the east. In fact the cowbird is known to parasitize more than 220 species of birds in this way! As a result of the loss of forests, cowbirds became the dreaded edge species as they would regularly venture into a forest for 100-200 metres, and interior forest bird species nesting within that zone were heavily parasitized. Some ornithologists consider interior forest to be a minimum of 100 metres from any edge, whereas other specialists consider interior forest to be at least 200 metres from an open edge. Currently most forests in southwestern Ontario have been reduced to the extent that there is very little good quality interior forest to prevent cowbirds from entering and impacting the interior breeding bird species. Wood Thrush, now a Species At Risk, is usually an interior forest species, but sometimes can be found near the edges especially when proper interior forest is diminishing.

 This next photo shows an adult cowbird visiting the nest of a Yellow-breasted Chat, an extremely rare breeding bird in Ontario. 

I took this photo in about 1980. This was the first confirmed nesting of the Yellow-breasted Chat at Rondeau, and one of the few in all of Ontario. It was well away from any real forest edge, although a severe windstorm had caused a lot of blow-down which resulted in some shrubby habitat dominated by raspberry. It was great habitat for chats, but cowbirds also made it into the area. Fortunately the young chats in the nest were well along in their development so that if a cowbird laid an egg, it would not hatch before the chats would likely have fledged.

If you would like to subscribe, or unsubscribe, to Nature Nuggets, send an email to: prairietramper@gmail.com

Rare Birds of the Rondeau Provincial Park area

Things are a little quieter in the middle of winter. Since birds are not so plentiful at the moment, I will discuss birds from a different perspective: rare birds of the Rondeau Provincial Park checklist area. This area covers the equivalent of the Christmas Bird Count circle and includes the entire park in addition to local areas such as Erieau, McGeachy Pond and both Blenheim and Ridgetown sewage lagoons, as well as places in between. Part of the rationale is because the park's official boundaries have changed a bit over the 125 years of its existence, and much of the surrounding area is likely influenced to some extent by the presence of the park. Also it enables the park checklist to include all of the CBC records; the CBC has been going since 1939, and it would be too difficult to separate all of the CBC records from the park specific ones.

Given that there are so many rarities that have been recorded, my current plant is to break it down into four categories/posts: rare breeding birds; rare migrants; very rare migrants; mega migrants. Other than the first category, the others are somewhat subjective as you may note as these posts unfold.

The bird records for Rondeau go back to well over a century. It has been birded heavily for many years, and not just for migrants, but also for breeding species. In fact if it hadn't been for the presence of that 'other' park along the shoreline just a few kilometres west of Rondeau which has been recognized nationally and internationally to a much greater degree, it is quite possible that Rondeau's status would be elevated much higher than it has. But most people I talk to are quite happy with the much smaller crowds to contend with at Rondeau.

With such an array of habitats in the most southern part of the country, it is not surprising that there is a large diversity of breeding and migrant species that have been recorded. At the moment, there are 365 species on the park checklist, one for every day of the year except for the current leap year. Hopefully we will get at least one new species in 2020! At least 148 have been confirmed breeding, with another 16 species that have shown evidence of 'Probable' breeding based on Ontario Breeding Bird Atlas criteria, but have not been confirmed. It is interesting to note that during the first Atlas of 1981-1985, one of the atlas squares that took in a large part of Rondeau recorded the most species with some breeding evidence, 146 species, of all of the atlas squares in the province! Another partial Rondeau square was also in the top ten, with 134 species.

Some of the photos I am including are taken from scanned slides back in the day when film was the only option. Clearly they are not up to the same quality as current digital images, as you will see. When film was king, the best photos were taken with ASA/ISO of 25 or 64, both Kodak products. If the photographer needed a little more 'push' to allow for faster shutter speed, he might step up to ASA/ISO of 100 or 200 with decent results. On rare occasions, film of 400 ASA/ISO might be used, but that was for record photos only. Publication editors frowned on anything greater than 64-100. But for these posts, if slides were all I had, that is what I used.

On to the rare breeding birds of the Rondeau area.

Acadian Flycatchers have had a sort of stronghold at Rondeau for decades. The abundance of American Beech, their preferred tree species to build their nest in, is certainly a main factor. While surveys have not been done for the species, it is fairly typical to find a few pairs even along the trails and roads, so who knows how many will be nesting in the much more extensive area beyond the travel of most birders. It is currently list as Endangered.

 Bald Eagles were considered Endangered in Ontario up until a few years ago. As recently as the 1960s the only active pair between Long Point and the Detroit River was at Rondeau, and for several years they were unable to fledge any young. The species has experienced a much improved outlook especially in the last couple of decades. Even in Chatham-Kent, there are currently about 18 known nests. It is now listed as Special Concern.

 Barn Swallow is currently listed as a Threatened species due to habitat loss, decline in insects, etc. That subject might be the focus of a future post.

 Black Tern is Special Concern, due to the decline in wetlands, and the ongoing deterioration of them due to invasive species. It used to be nesting in small numbers at Rondeau and area, but has declined considerably.

 Bobolink does not nest in the park proper, but does on some of the surrounding pasture lands and the grassland habitat around sewage lagoons. It is Threatened.

 This is the nest of Brewer's Blackbird, a very rare species at any time of year in the Rondeau area. A pair decided to nest in a small tree along the ditch just to the east of McGeachy Pond back in the '70s. This is our only known nesting.

 Cerulean Warbler is a Threatened species that used to occur in small numbers at Rondeau, especially where there were tall trees with large crowns along portions of Harrison Trail. They have declined throughout their Ontario range, and have only been seen on migration here in recent years.

Cerulean Warbler female

Cerulean Warbler male

The Chimney Swift is listed as a Threatened species. In recent decades it has nested almost entirely in chimneys, hence its name. There are very few chimneys at Rondeau that would be suitable, but I have seen them entering large, old hollow trees. Clearly before humans provided artificial structures, old hollow trees of old growth forests were undoubtedly the main nesting structure. With the ongoing loss of forests in general and especially the loss of old growth forest types, their future at least in parts of the province where forest cover is extremely low is not too bright.

 Common Nighthawk is listed as Special Concern. They would nest naturally in forests with partially open ground cover. They have adapted to flat roofed buildings, especially those with a tar and gravel base. There are old nesting records for Rondeau, and I have heard them calling in the early evening during the late spring and early summer from some of the ridges along the west side of the park.

 Dickcissel has been present as a breeding species in very small numbers for a few years. In 2017 there was a huge influx of them across southwestern Ontario especially, but certainly were also found north and east of this area. I wrote an article about this phenomenon in a recent issue of Ontario Birds, and you can read about it here.

 Forster's Tern is more of a western species. It was not known to nest at Rondeau until the later 1970s, when the marsh was quite attractive to them. It was a reliable nesting species for a few years, but in the last decade or so the habitat has declined due to water levels and invasive plant species, so Forster's Tern has not been documented nesting in recent years.

 King Rail is an Endangered species. It is secretive and difficult to detect unless it is calling from the depths of the large marshes where it occurs. The difficulty in accessing such marshes by birders hampers their detectability. Nonetheless there have been a very small number recorded in suitable habitat during the breeding season most years in the Rondeau area. The most recent confirmed nest was actually back in 1978, when a bird photographer friend and I photographed this bird and its nest at McGeachy Pond, near Erieau. As far as I am aware, it is the last time an actual nest has been found in Ontario, although other breeding evidence exists, such as fledged young running along berms, road edges or at the edges of marshes. A future post dealing with King Rail in more detail is in the works.

 Another marsh nesting species is Least Bittern. It is difficult to detect, but may be heard on a quiet night, or seen briefly as it flies low over the cattail and bulrush habitat it prefers. It is a Threatened species.

Little Gull is less common around the Rondeau area now than it was in the 70s and 80s. However as rare as it has always been, the first successful nesting of this species in all of North America occurred here, back in 1970. It actually attempted to nest in 1962 at the Oshawa Second Marsh, but was unsuccessful. The species had been seen at the southern end of the Rondeau marshes sporadically, but in 1970 there were two pair that fledged 8 young. It has not been known to nest at Rondeau since that time, but there are both adults and sub-adults seen at various times of the year in small numbers. It is always a highlight.

 Louisiana Waterthrush is a southern warbler species that is a Threatened species. There has been the occasional breeding record in Rondeau, which is a bit unusual since they prefer nesting near running water. I came across this nest in 1996 while doing a Prothonotary Warbler survey on a ridge west and south of the west end of Tuliptree Trail. It was in an upturned tree root right beside a large slough.

 Northern Mockingbird is generally considered to be a southern species, but it has occurred with some regularity across southern Ontario. There are a very few breeding records for the area.

 Orchard Oriole is another southern species that in the last couple of decades or so has become a more regularly seen species across southwestern Ontario.

 Piping Plover is an Endangered species that nests on open/grassy sandy beaches along the lake shore. Not surprisingly, it has nested at Rondeau in the past, but not for several decades. With the slightly improving numbers of this species throughout its range, maybe it will again be a breeding species at Rondeau, especially if the water levels recede a bit.

 Rondeau's and indeed the Carolinian Zone's, flagship breeding bird species is the Prothonotary Warbler. It is Endangered as it was never very common even in the Carolinian Zone, but has declined since the 1980s. The first breeding record for Canada occurred at Rondeau back in the very early 1930s. Since it likes mature forest with pools of water, Rondeau was ideal with its mature deciduous forest and the abundance of sloughs. In fact depending on water levels (and before Phragmites took over some of the better sloughs), it has been estimated that Rondeau had about 70 kilometres of available habitat. I did surveys for them at Rondeau back in 1983 and 1984, and even covering less than half of the best habitat, I came across about 24 singing males or actual pairs in a single year, so there could easily have been 50 pairs at Rondeau back then. The species does occur elsewhere in southwestern Ontario, but Rondeau has been the stronghold. Sadly, for various reasons, the Prothonotary Warbler has declined to the point where there is likely fewer than 20 pairs in total in Ontario.

 In the 70s and 80s all of the nests were observed in natural cavities. Since the early 1990s when efforts were made to assist the population, nest boxes were installed in some of the better habitat at Rondeau and elsewhere. The Tuliptree Trail of Rondeau has a couple of boxes which fortunately have attracted a pair annually so that it is one of the most reliable spots in Canada for birders to see this spectacular bird.

 Another spectacular breeding bird is the aptly named Red-headed Woodpecker. Its numbers have declined considerably across southern Ontario for various reasons. As a result it is listed as Special Concern. I can still remember on the 1983 CBC my territory included the southern end of Rondeau, and my colleagues and I counted more than 100 Red-headed Woodpeckers scattered in the trees at the very south end of the trail. It is unlikely that anyone will ever see this species in those numbers on one day again.

 White-eyed Vireo is not officially listed as anything on the species at risk list. It is just too uncommon a species which is normally found south of our border. Nonetheless it does appear as a periodic spring migrant, in very small numbers. And it was in 1971 when the first nest of this species in Ontario was discovered in the Bate's subdivision just north of Rondeau. Unfortunately the first nest was abandoned due to a cowbird egg being laid in it, and the subsequent nest, although it got to the stage when two vireo eggs were laid, also had a cowbird egg deposited. The vireo pair abandoned the nest and left the area.

 Wilson's Phalarope has nested in the Rondeau area on at least one occasion. It was at the Blenheim sewage lagoons, back in the day when cattails were allowed to grow in some of the cells, making the lagoons appear like a marsh. In some of the taller grasses on an adjacent berm was this Wilson's Phalarope nest.

 The females Wilson's Phalarope are the more colourful of the pair, as shown in the middle of this next photo.

 Wood Thrush has long been a regular nesting species at Rondeau. The deciduous woodland provides excellent habitat, although when the deer numbers were as high as 600 in the park, it changed the under storey to the point where it was less attractive to the thrushes. It still occurs, albeit in smaller numbers than before since the species overall numbers across its range has declined. It is listed as Special Concern.

 Yellow-breasted Chat is an Endangered species. It has nested at Rondeau on very rare occasion, and the nest shown here was the first one for the park. It occurred back in 1980, in a place off of the old Dillon Trail which had experienced a major blowdown from an ice storm. After a year or two, the ground layer grew into extensive stands of raspberries, much to the chat's liking. It has been around during the breeding season on occasion since then, but is a rarity even in migration let alone during the nesting season.

 On one occasion when I was photographing the nest, a Brown-headed Cowbird came by, presumably to consider removing one of the young and leaving one of its own eggs....or perhaps it stopped by just for a 'chat' :-). It must have detected my presence, as it left hurriedly and I only got this one photo of it at the chat nest.

There are some other quite rare birds that have shown evidence of breeding at Rondeau or in the area, but nesting has not been conclusive. Nonetheless they would be at least at the Probable level, based on the Atlas criteria. Here are some examples.

This first one is Blue Grosbeak. A Blue Grosbeak even on migration is noteworthy to birders, and it doesn't happen very often. However in 1995 a pair of them showed up in some good habitat a little west of Rondeau. There were several of us that tried to confirm its actual nest location but were unsuccessful, in part because it was on private land that was inaccessible. However we watched the male singing regularly as it patrolled its territory; we watched it interact with the female on several occasions, including copulation. After a few weeks of regular observation, the female seemed to have disappeared. It is possible that a fairly major storm event caused damage to the nest site or even the female itself. Or perhaps a marauding cat or raccoon found the female to its liking. Regardless, it was never confirmed with a nest or young, although a nest with eggs likely was present but beyond our access.

To add to the interest of this event, a male showed up in exactly the same place the following year, but without a mate. I have several pages of field notes from both years describing the encounter, as I was hoping that it would be the basis for an article in Ontario Birds, describing the first successful nesting of this species in Ontario.

  Hooded Warbler was considered a Species At Risk up until a few years ago. The Norfolk County area was its stronghold during the bleakest years for this southern species, but it has expanded to many other areas in southern Ontario. It has not been confirmed yet at Rondeau, but birds present in suitable habitat during the breeding season have been documented on occasion, and it likely has nested or at least attempted to nest.

Summer Tanager is a more frequently encountered southern species than Blue Grosbeak. Usually it is young males or females that appear in southern Ontario during spring migration. Even then it is rare when more than one individual shows up at a time in any place like Rondeau. In 1985, there was an influx of several Summer Tanagers at Rondeau, including adult males and females. A pair proceeded to exhibit various aspects of definite breeding behaviour along the western side of the South Point Trail. In spite of repeated visits and searches, it was never confirmed as the first nesting of this species in Ontario. I did write an article for Ontario Birds, and if you are interested, you can read about it in the December, 1988 issue, at this link.

 The White-winged Dove has been a showpiece at Rondeau for several years now, giving numerous birders their first look at this species in Ontario. The male, shown here, has attempted to build a nest on more than one occasion, perhaps with the intent of attracting a mate. Eventually one year, a female did appear, and there was breeding behaviour shown. However it might have been a little later in the season than it should have been for a successful nesting, as a nest was never found. Therefore while nesting was 'Probable' it has not been confirmed. Will 2020 be the year?

 Another reliable southern species was this Yellow-throated Warbler, which showed up for several springs and remained into the nesting period. A female was observed on occasion and there was evidence of an attempt at nesting, including copulation and the male carrying food (possibly to an incubating female). However in spite of experienced birders watching closely on many days, there was no conclusive evidence to confirm nesting. And sadly this bird has not been present for several years now.

There are other rare nesting species for the area, such as Northern Bobwhite (Endangered) and Eastern Whip-poor-will (Threatened) and Barn Owl (Endangered) but I have yet to get photos of them.

Next in this series will focus on some of the rare migrant species.