The Louisiana and the Cerulean

This video was recorded yesterday while revisiting the site where a Louisiana Waterthrush nest was found on May 26, 2010. The stream at this site is flowing with so much vigor that the two waterfalls severely limit the audibility of my playback system. Despite this I was able to locate a territorial male at the south end of the stream complex in a low valley sandwiched between two small ridges. I promptly ended playback as soon as the male responded and watched him for about ten minutes or so as he moved back and forth from the stream to higher perches. At one point he moved higher toward the canopy and was instantly chased off by a bill snapping small passerine, which turned out to be a female Cerulean Warbler (Dendroica cerulea). I followed the female for several minutes and hit an ornithological jackpot of sorts when she flew to a nest located on a horizontal branch of a large Sugar Maple (Acer saccharum), about 15m above the ground.

Cerulean Warblers build their nests high in the upper canopy of deciduous forests that have mature trees, little or no understorey and small gaps or breaks in canopy closure. These characteristics make their nests quite difficult to find and even harder to inspect and monitor! In this case I was able to get a decent view of the nest from either of the two ridges, which put me roughly 15 feet closer to the crown of the large trees growing in the valley. Even with this advantage I still had to zoom to 39x to get a low quality recording. Gotta thank the 749 mosquitoes for all the shakiness. I will definitely be returning to this site (with a tripod!) to monitor both of these important breeders in the next several weeks. Frontenac Provincial Park is one of the most significant protected areas for Canada’s population of Cerulean Warblers now listed as an Endangered species by COSEWIC.

Playback and Bullfrog at the falls

Back to the waterthrush surveys. Things have picked up a bit since my last post but it seems that 2011 will be marked as a down year for breeding Louisiana Waterthrushes in this region. I have not been successful at several reliable sites despite as many as four repeat visits. A review of historical records show some evidence of a downward trend occurring since the first half of the last decade. Despite an apparent population decrease coinciding with the initiation of our study in 2010 it is critical to monitor the sites through the good times and the bad times. Interestingly, the high number of unoccupied sites found this year has only buoyed my interest in the study going forward. Also, the 2011 season is not over yet as surveys at five more sites are yet to be completed and I do have four active sites to keep tabs on.

Ferns and Jack-in-the-Pulpit
Gorge near Birch Lake
Deer Fly season begins

the Nest Files – Louisiana Waterthrush

Female LOWA entering nest

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Louisiana Waterthrush (Seiurus moticilla)

Nidiologicals – Peck and James (1987) and Douglas Robinson (1995)

Habitat
– Gravel bottomed streams flowing through mature deciduous or mixed forest. Also nests in wooded swamp habitats on occasion.
Microhabitat – Nest built in cavities of stream banks, upturned tree roots or fallen logs.
Spring arrival – mid to late April (Ontario)
Average nest height – 0m (always nests on the ground)
Nest builder – male and female
Average # of broods/season – 1 (multiple broods not reported)
Average egg laying date – May 3 – June 12 (New York)
Average clutch size – 5 eggs
Incubation period – average 13 days
Egg colour – Whitish, spotted or blotched with ruddy brown, usually concentrated at large end
Incubation – female
Brown-headed Cowbird host – yes

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Nest building in progress

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Another FBS first – a Lousiana Waterthrush nest! A territorial pair was first located on May 10th at this site but no further breeding evidence was obtained at that time. A followup visit on May 20th revealed both the male and female building this nest in the stream bank above a waterfall. So why the delay? It’s possible that an earlier nest was abandoned but it is more likely that nest construction was delayed after the pair bonded, which is typical according to previous studies (Robinson 1990). On May 20th the pair were observed entering the nest site, which at that time was bascially a mud bowl with a bulky leaf exterior.  The pathway of leaves visible here is a common feature of a Louisiana Waterthrush nest but is not always built. The above photo illustrates this ‘pathway’ constructed of dead leaves, which are noticeably damp and likely collected from the water. The wet leaves and the addition of mud are probably used for adhesion and support of the nest exterior and pathway.

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Nest complete with eggs

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There were four eggs in the nest this morning, which suggests that egg laying began by May 22nd at the latest (1 egg is deposited per day). There might be one more egg still to come as the average clutch size is five (Bent 1953). I watched the female incubate for about an hour before she slipped away for a break. The male was present, he sang on two occasions nearby and made short excursions to the waterfall but never approached the nest. With the female on break, I approached the nest to check its contents and snap a few quick photos.

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Nest contents

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The interior of the nest had transformed since my last visit. What was formerly an excavated mud bowl had become a neatly constructed cup nest lined with fine grasses, rootlets and animal hair.

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This last photo shows the nest site context. This would be considered a fairly exposed nest site for the species. This spot wasn’t on my radar during my initial scan of the banks along the waterfall. There were several other sites that would have been more enclosed, shaded and difficult for non-avians to access. You can just barely see the stream bottom in the lower left corner. Luckily, relocating this nest has always been instantaneous thanks to the convenient tree root pointing to its location! Waterthrushes never fly directly to their nests, instead, they approach the nest by walking from a distance as great as 10m – very typical behaviour for ground nesters. This is nicely demonstrated by the following video of the female at the nest from this morning – whom I could have watched for hours if not for the oppressive heat today. If all goes well, the eggs will hatch in 8-10 days and I’ll be back to check on the family in early June.

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Finally, here is a short video of an adult female LOWA at the nest from today’s visit. Just to avoid any confusion, I should mention that during the video you might hear a Northern Waterthrush singing nearby. The two waterthrush species “get along” very well and exhibit little or no interspecific aggression (Craig 1984). The video can be viewed at higher resolution here.
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Big Salmon Lake by canoe

Common Loons (Big Salmon Lake)

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At nearly five kilometres long, Big Salmon Lake is the largest lake within Frontenac Provincial Park boundaries. The lake has over fifteen kilometres of shoreline and has a maximum depth of 42.3 metres. Bisecting the park along a northeast-southwest axis, Big Salmon has long been a gateway to the Frontenac backcountry and a focal point for early mining and logging industries. Geologically, the lake also marks a divide between two distinct zones – granitic gneiss and marble to the northwest and a large dome of diorite in the southeast.

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Yesterday, I ended up paddling the entire length of Big Salmon to reach two remote streams for the ongoing Louisiana Waterthrush inventory. This long oligotrophic lake was absolutely stunning and a joy to travel across. Steep cliff faces with ancient bonsai-like conifers, Cerulean Warblers singing from mature oak-maple canopies and windswept white and red pines on small rocky islands were just a few of the highlights during the trip.

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Canadian Tiger Swallowtail and Juvenal's Duskywing

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The sightseeing was a nice diversion but my main priority was to find two streams, which to me were nothing more than tiny blue lines on a map. I’ve visited fifteen streams so far this spring and never really know what I am going to encounter. Some streams are pristine, fast moving waterways in steep sloped ravines while others are completely dry and sun drenched. Regardless of their condition, the purpose of the project is to index as many sites as possible to evaluate current stream conditions, habitat preferences, aid future inventories, and to model population parameters of Louisiana Waterthrushes in the area.

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This particular stream was an absolute gem and ‘ticked all the boxes’ for Louisianas in terms of aquatic characteristics as well as slope, canopy closure and presence of suitable nest sites. The meandering stream was teeming with life. My survey of its length revealed a considerable forage base for waterthrushes and very high biodiversity with one glaring exception – no Louisiana Waterthrushes! There was no response to playback following an unsuccessful ground search for the species. This was surprising at first but a broader scan of the site indicated that the mature forest shading the stream was a relatively small patch bordered by younger growth and even small rock barrens. Louisiana Waterthrushes are area sensitive and therefore need large contiguous tracts of mature forest to breed, which would make this site unattractive. Forest succession might make this site suitable for LOWA in the not so distant future.

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The stream itself has been around for quite awhile, evidenced by the erosive passage of water over and through the rocks of the stream. The rectangular finger-shaped rock on the right in the photo above has water passing through it and looks oddly man-made. I’ve uploaded a short video clip of this interesting feature below.

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Green Frog

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Last but not least, a Green Frog (Rana clamitans), one of the many inhabitants of the stream. This fellow was sitting in the middle of the watercourse, faced upstream. Maybe this frog is just chillin’ but I think this might be an excellent way to catch some lunch – let the stream bring it right to you.

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I am starting to run out of accessible waterthrush sites but still have a few more left to visit before the whirlwind of our other breeding bird work begins in early June. I will miss these shady ravines….

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Waterthrush survey update

Louisiana Waterthrush - May 10, 2010

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It was a chilly start to this morning’s fieldwork but it turned into a great day on all fronts. Birds were more abundant and diverse today with many firsts of the year including Black-throated Blue Warbler, Broad-winged Hawk (two separate adults carrying food!), Solitary Sandpipers and a whopping great tally of 14 Cerulean Warblers. Yellow-throated Vireos and American Redstarts were also quite numerous.

I was thrilled to find a Northern Waterthrush in the midst of nest building along a creek near Birch Lake but the real star of the show today was the discovery of an actively nesting pair of Louisiana Waterthrushes. The pair were located in a deeply incised ravine in mature forest. I hung around for a bit to observe them and suspect that a nest containing eggs is likely to be found above the steep bank of a waterfall at the site. I didn’t have time to look for the nest but will return to the site at a later date for a checkup. To my knowledge this is a newly documented breeding location for the species.

The media file below includes pictures and a short recording of the male LOWA taken at the site this morning. Something went wonky with the image quality during conversion at Vimeo but the sound is accurate. The Louisiana Waterthrush (Seiurus motacilla) has a distinctive song, much softer, sweeter and melodic than the louder and more guttural warble of its cousin – the Northern Waterthrush (Seiurus noveboracensis).


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Nest under construction: Red-eyed Vireo

CLICK HERE to watch this video in High Definition on Vimeo

The above video was captured over a period of four and a half days from June 27-July 1, 2009. A female Red-eyed Vireo began installing the foundation of a nest in a young maple about two meters above the ground on June 27. The process in its entirety was fascinating to observe as the footage revealed subtleties of technique and the use of various materials.

The Red-eyed Vireo (Vireo olivaceus) is one of the most common passerines of eastern forests in North America. A neotropical migrant, “Red-eyes” migrate to South America each autumn where they feed primarily on fruit. During the summer they are dedicated insectivores of mainly deciduous forest stands and fragments. The male Red-eyed Vireo is a vocal standout in the avian world as they hold the record for most songs per day of any bird species on the planet. In June and July the female Red-eyed Vireo builds a pensile or suspended cup nest from an outer fork of a branch-exclusively in deciduous tree species. The subject nest of this writing matches this description very closely. This particular nest was easily accessible for monitoring, providing a convenient window into the meticulous and masterful work of the nest building songbird.

I strongly recommend that you watch the HD version of the video to see the subtle movements and to appreciate the remarkable precision of the bill in manipulating nest material. The video clearly shows how important spiders and their webs are to nest construction for this and many other bird species. The female worked constantly during daylight hours over the course of four days. Review of the footage indicated that she visited the nest for periods of between three seconds to two minutes with an average of four minutes between trips. This rate would mean that just shy of 200 visits to the nest are made each day for a total of ~850 visits to complete a nest in four to five days!