Another nature walk and another muskrat sitting in the bath going to town with its vegetables. It seems that every time I come across muskrats they seem to be eating. Maybe they are just more conspicuous when they are eating…, or maybe they are just always eating, just like human teenagers. I imagine one would have to chomp down quite a bit of vegetables to get your daily nutrient requirements. Just like me, muskrats are facultative herbivores which means that they prefer to eat plants but, if necessary, can also consume animal such as fish, frogs and insects. The other day as I was out by a lake with some young ones we spotted a muskrat swimming around and, too my surprise, not eating (but it was probably looking for food). When the kids saw it they immediately identified it as a beaver. To be entirely honest, the first time I saw a muskrat I also mistook it for a beaver. The muskrat is like the lesser known cousin of the superstar beaver in that everyone recognizes a beaver (even if they have never seen one) while few people recognizes the muskrat (even if you might be looking at one). Perhaps the easiest way to tell these semi-aquatic rodents apart, particularly if it is your first time seeing one, is the tail. Beaver with its tell-tale flat and paddle-shaped tail while the muskrat has a long, skinny tail with flat sides. If you can see the tail there really is no way of mis-identifying a muskrat for a beaver. In the picture below you can clearly see the long skinny tail of the muskrat. Once you become a more seasoned muskrat aficionado you realize that there are a few other distinguishing characteristics as well. Perhaps the most obvious difference (if you know about it) is the size difference. Beavers are huge weighing in at between 35 and 60 pounds while muskrats are puny in comparison topping out at about 4 pounds. Another difference is that with muskrats you can usually see its whole body when it is swimming while with beavers you typically only see their large wedge-shaped head. While I have not seen a beaver at the creek for a while the musk rats are out in full force.
As I crossed the pedestrian bridge across the Whitemud Creek a lone female Common Goldeneye (Bucephalus clangula) was swimming around in the creek eyeing me curiously. Common Goldeneyes are medium-sized diving ducks where the females are brunettes with a piercing golden-yellow eye. There are two species of goldeneyes, the Common Goldeneye, which as the name suggests is more common, and, the more rare, Barrow’s Goldeneye. While the males of the two species are easy to tell apart, the females are more difficult to distinguish as they appear nearly identical. According to Sibley the Barrow’s Goldeneye female has a darker brown head than the Common Goldeneye which does not help me at all since I did not have the two species next to each other for comparison. Perhaps the best distinguishing characteristic between the females of the two species for someone like me that has only seen a handful of these species is the bill color. According to Sibley the female Barrow’s Goldeneye has a “usually mostly yellow” bill while the female of the Common Goldeneye has a “usually mostly black” bill. Looking at the picture I would say that her bill is definitely in the category “mostly black”; ergo, it is a Common Goldeneye.
Yesterday I went for a nature walk to a part of the Whitemud Creek that is located south of the 23rd Avenue. I have not been to this location previously and I just happened to run some errands in this neighbourhood so I decided to “kill two birds with one stone” and squeeze in a short nature walk in-between errands. As it turns out this part of the creek flows through the Mactaggard Sanctuary, a 104 hectares nature sanctuary, part of which was donated to the University of Alberta in 1980 by Sandy A. Mactaggard, a developer and philanthropist. The sanctuary has a interesting history, which also explains why it is called a “sanctuary” and not a “park”. There is a video where the late Mr. Mactaggard tells the story behind the sanctuary. In short, the sanctuary used to be located outside of Edmonton when Sandy Mactaggard originally purchased the land for housing development, but only after promising the previous owner of the land that he will preserve it to benefit the citizens of Edmonton. The purpose was not to turn it into another park, but rather keep it pristine and let it remain the way it always had been. That is why it became a sanctuary. The trails along this part of the creek are more untamed and rough with less traffic.
I did not have much time for my nature walk so I had to move quick and as a result did not get much birding done. My main aim was to find a large oxbow lake situated in the sanctuary and do some preliminary scouting to figure out how to access the lake. Oxbow lakes are often enveloped in dense vegetation and can be difficult to find and access. The benefit of this is that many animals use these lakes for raising their young. I did not have any trouble finding the lake as the trail briefly passes right along side of it, but just as I suspected most of the lake is surrounded by dense vegetation. Accessing the more remote parts of the lake (the ones where the trail did not go) proved, however, to be even more difficult than I had anticipated as the entire outside rim of the lake is surrounded by a high and very steep bank (almost like an overgrown cliff) and there was not obvious way of accessing the shoreline. There is a trail, the Mactaggard sanctuary loop trail, that loops around the lake ascending the steep bank. Although this quick exploration gave me some ideas of how one might be able to access some of the more remote parts of the lake, I did not have time to look into the feasibility of any of these possibilites. That will have to be another excursion. On a different note, the mosquitos were voracious and I did not bring any repellent so, this is a reminder to myself not to forget the repellent next time.
The first time I ran into the conundrum of how to quantify the number of individuals in a large flock of birds was as at the edge of the Pacific Ocean at Boca Budi in southern Chile. On the cliff face overlooking the Pacific Ocean we encountered a colony of nesting Red-legged Cormorants (Phalacrocorax gaimardi). Our best estimated was that the visible portion of their cliff had a minimum of 300 individuals, a number that was likely an underestimate. Here is a link to the eBird checklist. The second time I ran into the same problem, albeit on a different magnitude, was at a small pond outside of Tofield (Alberta) full of snow geese (Anser caerulescens). Our best estimate was that there were 15000 geese on the water and in their air. Here is a link to the eBird checklist. Both times we had no particular estimation strategy, but rather we based our estimates on eyeballing and whatever “common sense” we had (whatever that means in this context). A few weeks ago we encountered a large flock of Canada Geese taking off from a farmer’s field outside of Camrose, this time I decided to go about the estimation more systematically by using one of the photos I took of the fleeing geese.
Once I had the photo on my computer screen I proceeded by according to the following steps:
I started by dividing up the image into a grid (see image below).
I counted each bird in the grid cell with a green outline. There were 23 individuals in this cell.
I used the patter from this cell to estimate the number of individuals in every other cell. The estimates are in yellow and fall into four categories, “looks like 23”, “looks like half of 23, i.e. 12”, “looks less than half, i.e. 5” or “no birds = 0”.
I added up the estimates (the yellow numbers) and got an estimate of 436 geese.
To check how good my estimated was I then counted the actual number of individuals in each grid cell (note the blue dots), indicated in blue numbers, and added it up. There are exactly 422 geese in the picture.
The estimate is not to shabby but obviously begs the question how one would (could) modify this approach to do “live” estimates in the field. I guess doing a “posts-observation” estimate like this is also fine to as long as all the birds are in the picture to start with.
The main issue with this estimate is that the image does not include all the geese. There were plenty more geese both to the right and left of the picture. This estimate was more a proof of concept exercise that still needs to be refined to be useful in the field when you have a gaggle of geese flying by in a matter of seconds.
Along a forested section of the trail looping around the First Lake on the Valley of the Five Lakes trail we encountered these small purple flowers poking through the thick moss cover. They had an “orchidy” sort of look to them but at the time I did not know what they were. It turns out they they are indeed orchids known by various names, including, Calypso Orchid, Venus’ Slipper or Fairy Slipper (Calypso bulbosa var. americana). It is a circumpolar perennial orchid found in undisturbed montane forests. They belong to the genus Calypso, which only contains this one species, which takes its name from Greek signifying concealment, as they tend to favour sheltered and undisturbed areas of conifer forest floors. Although it is wide spread globally it is considered threatened or endangered in some part of the world (e.g. several U.S. states and in Sweden and Finland) as it is sensitive to disturbances and has a rather finicky reproductive strategy. It relies on visits by pollinating insects, specifically bumblebees here in Alberta, by deception as it does not produce any nectar to reward its pollinators. As a result insects quickly learn not to visit it again. Talk about burning your bridges reproductively.
Something was definitely moving along the water’s edge, we just could not immediately focus in on it. It took us a while to adjust our eyes and calibrate our brain to pick up the small stealthy bird scurrying around on the sandy shore on the opposite side of the creek. It was a small shorebird with spotted underparts and sand brown upper parts. If it would not move around it would be nearly impossible to see against the sand and pebbles along the shoreline. I have not seen many shorebirds in my life and this one was definitely a new one. While it was working the shoreline for a morsel to eat its tail was continuously bobbing up and down. Ultimately, this is what gave it away…, it was a Spotted Sandpiper (Actitis macularius, Lifer #162, AB Big Year #114). The Spotted Sandpiper is a true American as it can be found from the Canadian high arctic during the boreal summer down to the shorelines of Chile during the austral summer.
The very first bird we spotted as we arrived at the oxbow pond down at the Whitemud ravine was a male mallard that was snoozing on a log. The log was covered in lush greenery with the mallard cosy like a bug in a rug in the greenery. It was very idyllic and looked quite comfortable. Oxbow ponds are unique habitats where the water is still and stagnant compared to the rushing water in the creek. There are rumours of numerous oxbow ponds along the Whitemud creek. So far I have found two, both almost entirely covered with thick riparian vegetation making them surprisingly difficult to spot although they are only steps away from the trail. This particular oxbow is the largest one I have found so far and is bound by an old beaver dam at the north end and a wall of accreted sediments on the south end. Groundwater and seepage from the west side of the ravine feeds the oxbow, as does spring and surface runoff. Other than seasonal fluctuations in the water level the water is completely still in these pond.