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Ospreys on Colonel By Lake 

By Henk Wevers


In 2002, Jack Golden, our neighbour, erects a tall pole with a large wooden platform on the top for ospreys to nest. It has a commanding view of Colonel By Lake and is surrounded by some open space with tall willow trees nearby. The trees provide plenty of overhanging branches for the birds to perch; Jack has chosen the nesting site very well.

Not long thereafter we see ospreys, also known as fish hawks, circle the platform. They take their time to inspect it, and a few days later sit contemplatively on the edge of the platform and in the neighbouring trees. However, the birds move on, and the nest remains empty.


Early April 2003, a mound of large dry sticks piles up on the platform. The pieces are woven into a deep circular nest. Thinner twigs and branches line the nest and extend well over the edge. One day, not long after the building of the nest, Jack likes to see what is going on and he inspects the nest using a ladder. He leaves the ladder overnight leaning against the pole and a raccoon or other predator uses the opportunity to have dinner. The birds leave and may have moved elsewhere, or they will remain single for the rest of the season. After this failure there is no more human interference and to make sure that predators can not climb up the pole, Jack covers it with a large sheet of metal about eight feet from the ground. We hope the birds might give the nesting site another chance. But we have to wait until the next season; will they come back..? 


Late March 2004, the ice on the lake has melted, the shrubs and trees along the shore are a haze of light yellow-green, early migratory birds are back, hundreds of geese and ducks are feeding in the shallow waters of the bays and use the centre of the lake as a rest-stop on their way to more northerly breeding grounds.  With the snow gone on the road, we can ride our bicycles again.

Early April, we notice two ospreys circling the nesting site; the birds are easily recognizable with their large wingspan, streamlined bodies and elegant flight. They soar high in the sky, contrasting sharply against the white clouds and blue background; their arrival buoys our spirits.

The birds settle in and soon one of them sits patiently in her nest, its head barely noticeable at times. Its mate hunts or perches on a branch nearby. The nest is about fifty meters from the road and we can easily observe the ospreys when we are out bicycling. We can also see them, with the aid of a telescope, about four hundred meters across the bay from our house. In early June one of the ospreys no longer is in the nest but perches on the edge while her partner sits on a branch of the nearest tree. Have the eggs hatched?  The incubation time is about 28 days. There might well be chicks by now, but the nest is very deep and it will take a while for any signs of the little ones.

In early July three chicks frequently pop up above the rim of the nest. They are less than half the size of the adults. Sometimes they sit side by side on the edge of the nest. On a very clear day their orange brown plumage and white chest, a white face and dark brown cheek patches stand out in the bright light.

“Three chicks is a very good brood,” says our friend, a field naturalist. “The lake must be healthy to support this large family.”

The lake, called Colonel By Lake, just north of Kingston, ON, is about two kilometers wide and six kilometers long; it is part of the Rideau Canal that runs between Kingston and Ottawa. The lake was formed in 1832 at the completion of the canal project when the Cataraqui Creek, flowing through low lying forests and farmland, drowned under the rising water held back by the dykes and locks at Kingston Mills. Before that time, the creek rushed through a natural cut in the granite bedrock formations at Kingston Mills into the Cataraqui River. This river flows into Lake Ontario at the confluence with the St. Lawrence River.

In the spring, the falls are powerful, boiling with excess runoff that bypasses the locks. In the summer and fall, water only trickles over the smooth, granite. The bulk of the water is then channeled through the four lock chambers, lowering boats 47 feet to the level of Lake Ontario in the direction of Kingston.

Where the creek runs below the surface of the lake, the water is eighteen feet deep; near the shore it is shallow. Several swampy bays, rich in wildlife, surround Colonel By Lake. The bays are the nurseries and hiding places for many species: turtles, frogs and fish. These are also the hunting grounds for predators such as heron, otter, raccoon, fisher and the occasional bald eagle.

Colonel By Lake is low in contaminants and has a healthy population of large-mouth bass, pike, and perch and, of course, sunfish. North of Aragon Road, which runs parallel with the shore of the lake, are agricultural fields on rich glacial till; between the road and the lake are acres of wetlands, forest, and shrub land teeming with terrestrial wildlife and birds. The biological richness of the lake and its littoral are the reason the ospreys have chosen to breed there.

Over several years of observation, the habits of “our” ospreys become better known. It is clear that they indeed need a large body of water, well stocked with fish, as part of their habitat. The parents are hunting constantly to feed the hungry brood and themselves. They frequently fly in with a fish aligned with their body to lighten the drag. They come in on a glide path and at the last moment elegantly swoop up to well above the nest when, with wings spread high above their body, they stall in mid air and then land effortlessly on the edge of the nest. While one partner eats the catch and feeds the young, the other rests on a tree branch. A little later, the hunt starts all over again. The bird flies south over the horizon in the direction of the Cataraqui River, below the locks, where the river is broad and rimmed with large, beautiful marshes. We also see the birds flying northwest towards Collins Bay Lake, east to the River Styx and to the smaller, secluded, bays in Colonel By Lake. They fly easily five to eight kilometers to their fishing grounds.

Osprey chicks hatch a week or so apart. Later on, the difference in size is noticeable when the parents feed them. The larger chick eats first, followed by the middle one and then the smallest; very different from songbirds where the whole clutch of young make an impatient racket when food arrives.

In the early stages, the osprey parent gently offers little bits of fish to the chick that is barely recognizable, only the head bobs up over the edge of the nest. It gently takes the morsels from the parent bird. In between, the parent forcefully tears a large strip of flesh off the prey and eats it herself. After a few quick hungry bites, the large powerful bird changes its posture and becomes gentler, patiently feeding her chick. When the chicks are growing rapidly, from the middle of June to the middle of July, they eat about three to four kilograms of fish every day, according to the literature. After digestion, secretion is rather spectacular: the chick wiggles and moves its rear end over the edge of the nest, its head and body dipping, before ejecting a large plume of white liquid at a forty five degree angle, several meters high into the air.

While the chicks grow, the nest needs maintenance. One day, one of the adult birds is busy reinforcing the nest. It flies in with a large heavy branch held firmly in its beak. The branch is much longer than its wingspan, maybe two meters or almost eight feet long. At the same time, its mate is eating a fish, seemingly oblivious to the hard work. The bird thrusts the stick at a slant in the side of the nest and re-arranges it several times until it is an integral part of the enlarged nest.

The chicks are only occasionally in view, often they stay low in the nest. Sometimes a grey brown mottled wing appears from the center of the nest, slanting up in the air. At the same time, a little head bobs up in another location. They seem to be fed all day and share whatever the parents are able to catch. Both adults are hunting throughout the day, but early in the morning and later in the afternoon seem to be the busiest times. At these peak feeding times the nesting site resembles a fish processing plant: fish arrives, is filleted on the spot, some of it is eaten by the adults, most of it goes to the hungry chicks, the digested fish goes overboard, a fresh catch arrives…

Later the feeding pattern changes: a parent often ignores the hungry chick instead encouraging it to pick at the prey by itself. The chick mimics the thrusting of the head while pecking at the prey, after a short while the chick is rewarded with a piece fed by the parent. Not long after, the chick tears off the pieces by itself.  While this evolves, the younger chick is still in the baby-feeding mode.

Several days later, an osprey flies in with a fish. While it lands on the nest, its mate flies off over the lake to the river. Instead of eating the fish on the nest and sharing it with the chick, as it normally would do, the adult flies to the nearby tree and eats its prey alone. The fish hangs limp on the tree branch while the bird rips it apart. The chick seems disappointed and confused. Maybe it is time to figure out how to get food by itself?

In early July, the three young start spreading their wings, first hesitantly then more confidently. A little later, during these exercises, the oldest chick becomes airborne for just a second, vertically taking off from one side of the nest, and landing, somewhat unsure of itself, on the other side. A few days later, the juvenile flaps its wings and rises one… two… meters straight up; it hovers over the nest for several seconds, flapping its large wings energetically.

During the following days, the oldest chick flies around and starts perching in the trees, near the nest. Over the next week, the younger siblings take turns in practicing flight, and in mid July all the young are able to fly.

In the month of August, the five ospreys: mother, father, and the three youngsters, are almost indistinguishable in size. When one or more are on the nest, the brownish black plumage of the young, distinguish them from the parents. But when they are flying or perching they look full-grown. The ospreys now often leave the nest from morning to late afternoon. In the evening one or two birds occupy the nest; the others rest in the nearby trees, a healthy looking family of five.

In early September, only one bird sits occasionally on the nest, mostly in the evening before sunset. Then, towards the middle of the month we no longer see them in our neighbourhood. The sun sets much earlier. At night, the temperature drops to the single digits. Trees change colour. While nature’s clues are subtle, the finely tuned senses of the ospreys give the signal to start exploring areas towards the south.

We miss the fish hawks, especially during the long winter when Colonel By Lake is covered by a meter of ice and snow. We imagine the birds hunting near the Atlantic coast, somewhere in Carolina or Florida; maybe they winter nearer, wherever there is open water and fish to catch.

There is plenty of time during the winter to reminisce and to speculate: “will the ospreys come back next spring?” So far, they did. Late March 2009, we saw the ospreys again circling the nest. A few days later one of the birds sat on the nest, huddled low, most likely hatching a clutch of eggs.

 From 2004 until 2008, ”our” ospreys brought up fourteen offspring!


 Between 2009 and 2010 two more nests have been established around the lake.

One in a high dead fir tree on one of the bays called Esther Bay between the lake and the Aragon Road.

The other nest was built on a large tree stump dating back to the drowning of the land in 1832; it sticks about two meters or eight feet out of the water in a bay just outside the navigational area at the beginning of the canal to the River Styx, going east from Kingston Mills.

The original and these two newer nests are about one kilometer apart.

 Colonel By Lake is indeed a welcoming habitat. 


Update 2009 and 2010:

In both years the pair have hatched three chicks, all flew out of their nest around the middle of July with the oldest going first and the smallest chick following about two weeks later. They return to the nest to feed, but in August the nest gets less and less used, and we see them all around the lake and its littoral. 2011 they arrived April 1, no kidding!


Update 2011:

On April 1, the ospreys are back. Our neighbours see them about the same time as we observe the birds circling around their nest. We assume this pair is the one that settled here in 2003 and then hatched their first clutch of eggs in 2004.

 On April 10, we noticed one of the birds sitting deep down in the nest, and we assume that there are eggs to hatch. How many? That has to wait; we only see them from our observation post when the chicks have grown up a little and hesitantly show their naked heads over the edge of the nest.

The eggs must have hatched around May 1st, we assume, one of the parents does no longer sit continuously deep in the nest, instead, the it stands on the edge watching over her brood, and waiting for her partner to bring back a fish, so she can feed their young.

In the next several weeks the chicks will grow and start exploring the world around them. That happens somewhere in June when our neighbour, who is closest to the nest, thought she could see three chicks stick their bald heads and skinny necks over the edge of the nest. On June 24 when the chicks have already grown to about two thirds the size of their parents, I can see them crowding just above the edge of the large nest; yes there are three offspring, again! This couple had once two chicks, and all the other years they hatched three young, a good number; our lake must be in a good condition with an ample supply of fish, and the parents appear be in good health.

Over the month of June we see more and more activity in the nest: occasionally a rather large wing is stretched out by a chick we cannot see, a somewhat disjointed impression of a growing baby osprey. One parent remains on the edge of the nest all the time, while her mate is hunting for food and frequently lands on the edge and deposits a fish, about 20 to 25 centimeters long.

In early July the activities in and around the nest start to peak, the chicks look now almost as big as the parents, their backs are speckled with brown spots, otherwise they look very much like a full grown osprey. Both parents hunt for food, to eat and to feed their big, hungry, offspring.

On July 8 I observe one parent flying in with a fish, but it starts to eat without feeding the young who seems surprised, but the oldest chick, slightly larger then the others, attempts to pick at the food itself. Apparently time has come to take a little more initiative towards feeding. No longer will the parent put the right size of a morsel of fish meat into the chick’s beak.

The juveniles are practicing their flight muscles again. Near the nest is a pair of Common Terns circling, soaring and diving, as if to show the young ospreys what can be done with a pair of wings!

Two days later I see the largest of the three juvenile birds fly off; it glides and then soars in front of the nest as if it wants to show off its achievement. I can see the brown speckled back. After making a large turn it swoops back on the platform, folds its wings and starts preening; mission accomplished!

The other two young are practicing flight by hovering over the nest or by lifting off and landing on the other edge. Sometimes they hover as high as two meters above the nest. Their wings are very large in comparison with their young bodies. Their wingspan is easily as wide as the large platform, close to four feet maybe?

During one of my next observations I see a young flying-in with its prey, she lands expertly and starts eating, all by herself, of course.

On July 15, at 7 am, only one juvenile stands forlorn on the edge of the nest, gazing over the lake. Two hours later I look again and one of the parents has landed a fish, but it ignores her youngest offspring and ferociously tears at the catch devouring strips of meat and other body parts. After about twenty minutes the parent shares the remainder with the young bird. Then it is off again and the smallest of the three juveniles is left behind… The message is clear; if you want food, find it yourself!

July 16, the nest stands empty. I look several times all morning, but the nest remains empty…

The family hangs around in the many trees that surround the nesting area, but I cannot see them from my vantage point. They will come back one at the time or have a family reunion once and a while, but in the coming weeks, the young will practice their flight and venture farther and farther afield, exploring the wider area for future nesting sites? There are some recently erected platforms along the lake and we have seen one already with the beginnings of a nest. Maybe we will have some of the younger generations coming back as mature breeding couples, usually after they skip one season to mature in their summering areas. The past years have shown much promise!

July 18, we bicycle past the nest and see one of the birds sitting on the edge, two are perched in a nearby tree and two are in the air, they seem to enjoy the updrafts caused by the SW-winds hitting the wooded ridge, a remnant of ancient glaciers.

When we come back after about fifteen minutes there is much commotion; all five birds are in the air and two are attacking a large Blue Heron that had the misfortune to select a fishing spot right under the osprey nest. Could the heron have known with all five birds in the air somewhere and the nest just a static landmark? The heron seeks shelter deeper under overhanging tree branches, but after a short while flies out of its hiding. All five ospreys now pursue the heron. To defend itself, the heron lands in the water, and from that position holds-off the diving ospreys with its formidable beak. As soon as the heron sees a chance she lifts out off the water she tries to fly away, but only a very short distance before the diving ospreys drive her back in the water. This is repeated five, six, times or more and we become concerned that the heron cannot keep doing this energy consuming manoeuvre for too long; the ospreys might just tire her out and drown her. Finally the heron escapes and just as we think she is safe, halfway across the lake, a distance of about one kilometer from the nest, one osprey dives again and chases the heron back in the water another two or three times. We can just see the heron finally flying away and the osprey returning to her base… What a spectacle!

On August 30 we see the family around the area, but less and less so, during September we don’t notice them anymore, they may still be near and occasionally seen above our lake, but we assume they have moved on; see you all next year…?


 Update 2012 

Between the spring of 2002 and 2008 we observed ospreys settling our neighbourhood, on Colonel By Lake, north of Kingston Mills. This was reported in an article published in the June 2009 issue of The Blue Bill. Much has happened since that might be of interest.

From the time when the first pair of birds arrived in 2002 and successfully hatched their first offspring in 2004, they have brought up twenty-three young to date. Some of these have set up nests around the lake as shown on the map in Figure 1. This assumes, of course, that the first couple have now reached late adulthood and returned every spring, and that some of the young adults tend to nest in the area where they were brought up, after teaming up with mates from other families.

The first new pair to arrive in 2006 must have been two years old, which is the earliest couples form, and they built a nest on a large tree stump in the shallow waters at the east end of the lake. This nesting site was used until 2009 when the couple abandoned it. The pair produced one and then two young each year until they moved on. In 2010 we spotted a large nest on another tree stump in shallow water in the River Styx about one and a halve kilometer north-north east of the abandoned site; would this be the same “tree stump loving” pair?  We can observe their activity only from a large distance, but the nest looks well built and we can spot the parents taking care of their brood in the years to date. Another keen observer, who operates from a kayak and can come closer to some locations, related to us that they have three chicks this season. [1]

osprey dickinson 3 may 2010

 Photo credit: Jeff  De Ruyter

About eight feet of an old tree , already over hundred years old when  in 1832 Colonel By Lake was created by flooding north of Kingston Mills. The stump is about hundred feet from the shore.


In 2007 another duo built a productive nest on the shore of Esther Bay, part of the watershed, between Colonel By Lake and the Aragon Road. It lasted until 2010 when a storm toppled the tree supporting the nest, with the loss of the brood. The next year, 2010, we assume with some confidence, this couple set up a household to the southeast, which is productive to date. See solid arrow in map

.osprey esther marsh july 13 09 joung wings spread

Photo credit: Henk Wevers


Also in 2010 a nest was built in a large dead pine tree bordering Colonel By Lake on the western shore. It can be seen from Kingston Mills Road. From 2010 to date it has produced two offspring each year, we noticed again two chicks in early July.

osprey ki mills bay june 29 2011 b

Photo credit: Henk Wevers


A neighbour at the end of Aragon Road erected in 2009, on a large tract of land, two poles with a platform on each, offering more nesting sites. In 2011 one of these, nearest to the canal between Colonel By Lake and the river Styx, was occupied and it has been productive to date. We observed two young in early July.

osprey harriet pt july 18 2012 fledglings b

Photo credit:: Henk Wevers


There are now six occupied nests around Colonel By Lake and nearby River Styx. This might have been seven if one nest, on a high pole at the south side of the lake, was not taken away from an earlier osprey couple by two Canada geese! These geese arrive one or two weeks before the ospreys and start hatching their eggs in early March. Many more geese breed in the marshy areas of the lake and it is no wonder the geese population on our lake is increasing exponentially… 

In the meantime, the original pair of ospreys is now in their tenth year of breeding and we have a precise insight in their behavior since we can observe their actions any time during the day from our deck, while we visit the other sites by boat, less frequently. It might therefore be worthwhile to report on the original couple in detail, as 2012 has been quite different from previous years.


The Original Couple, in its tenth year of breeding

 On March 19th , earlier than in the past, we observe an osprey flying around the old nest site dating back to 2002. Three days later, while the weather is cold and rainy, one bird sits forlorn on the edge of the large nest, waiting… Just about a week later there are two ospreys and on April 3 we observe one of the parents, the female we assume, squatting deep in her nest. It is still cold, but we hope that this practiced adult will be able to hatch another batch. We have to wait and find out what the number of young birds will be this time…

Almost six-seven weeks later the parent is still sitting in the nest, but on May 25, we see one parent perching on the edge while the other sails high up in the air to look for prey. A little head is barely perceptible above the edge of the large nest. After a few days we confirm that there is only one chick.

The next day one bird flies in with a large stick in its beak to make the nest a little larger and the edge sturdier, who knows what the bird’s engineering instinct tells it to do? Below the platform on which the large nest is built we see a houseguest: a small bird flies in and out to bring up its own brood. The ospreys above are oblivious to the small intruder below. We have observed the same at another osprey site; the little bird flies past our boat hunting for insects, a tree swallow? In any case since ospreys viciously attack any larger bird entering their air space, the little bird’s household should be among the most secure anywhere!

On June 9th we can clearly see the chick taking food from its parent. It looks about one third the size of the adult. A week later a wobbly fledgling stands on the edge of the nest; it is now about half the size of the adult.

On June 27th the fledgling, almost adult size, perches alone on the edge of the nest, both Pa and Ma are hunting for food. With only on chick to feed this might be a much-deserved break from the hectic schedule for providing three young in one season, which happened most years.

Why would this couple only have one offspring this time around? All other times they had three chicks, except for one year when they had two. Are the parents growing old? They are, after all, in their tenth year of breeding. They arrived in our neck of the woods as a couple in 2002; they had grown up as singles over a two or three years period before they met and attempted to breed. Their first successful attempt was in 2003 but this did not last. Then in 2004, and in the following eight years, they returned each spring and bred successfully. Therefore they are most likely about twelve to fourteen years of age and they are now senior birds since the average lifespan of ospreys is 14-20 years? [2]The very early arrival, this year, or their age may have been the reason they only had one chick.

On June 30th the lone fledgling is practicing flight on the edge of the nest. The next day it is airborne and makes a small hop from on side to the other. When we look through our telescope again on July 8, the nest is empty.

The following days we see the threesome, two parents and fledgling, in trees nearby or soaring in the air, it must be an exhilarating experience to suddenly be a master of flight. The birds clearly enjoy soaring on the updrafts over land. We would love to see the parents teach its young to catch fish, but that happens beyond our sight. We did see an osprey diving several times unsuccessfully to try catching a fish. On the other hand we also see them regularly flying towards their nest with a fish, torpedo like in their claws. And because this one young grew up quickly, two or more weeks before the chicks in the other nests have matured to fledglings, there must be enough food to be caught and with some practice the young bird will thrive. Soon they will explore Collins Bay Lake to the northwest and the Cataraqui River towards the southwest and beyond.

Will the birds come back in the evening to enjoy some rest and life as a family? They usually do until late August, early September, when they appear to migrate to warmer areas to the southeast.

Only fifty percent of the young will on average survive their first year, there will be more loss over the years, but Colonel By Lake and its surroundings, appears to be attractive territory for the many osprey couples and their young.


  The map shows Kingston Mills at the left margin, Colonel By Lake, Esther Bay to the north, and the canal connecting the lake with the River Styx. The nest sites are drawn in with the size of each star indicating the length of time they have been used. In the text box are the years of active breeding. We very much enjoy the expansion of the one nest starting in 2002 to six nests in 2012.

osprey map 2013

 Map adapted from nautical map by Henk Wevers


osprey river styx aug 2014

Photo credit: Henk Wevers

The  couple of ospreys built this nest, starting 2010 in the western corner of the large bay in the River Styx, just beyond the hand dug canal between Colonel By Lake and the River Styx. It grew in size and this photo is taken in July, 2014. In 2012 Mark Fleming reinforced the nest during the winter the boards he used can  be seen at the left below the mound of sticks.

[1] Mark Fleming, Aragon Road, Glenburnie, Ontario

[2] United States National Museum, Bulletin 167, pages 352-379


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