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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Lookin’ for Louisiana Waterthrushes

Devil Lake Creek

In Canada, the Louisiana Waterthrush (Seirus motacilla) has a small range limited to southern Ontario and Quebec. The population is small, estimated at <200 pairs, and restricted to mature forested ravines with clear, gravel-bottomed streams and/or woodland swamps. Louisianas are considered “area sensitive”. According to a Maryland study (Robbins 1979) a minimum of 100 contiguous hectares of mature habitat is needed for successful breeding (McCracken 2006). In Ontario, the Louisiana Waterthrush is a rare but regular breeder in southwestern Ontario. Smaller numbers also occur in deeply incised valleys of the Frontenac Arch where mature forest is present.

Playback equipment

The Frontenac Arch sits at the northern limit of the continental breeding range for Louisiana Waterthrush. Here, annual occupancy and productivity of breeding sites are probably influenced by weather cycles and periodic expansion/contraction of the source population further south, possibly upstate New York. It is suggested that north wandering immigrants cause a “rescue effect” for the Canadian population. There is also evidence of the species expanding its range northward, likely in response to maturing second growth forest cover. Climate change, beavers and water quality are also important influences on the status of the species in the Frontenac Arch.

We have started an inventory of Louisianas in Frontenac Provincial Park and in accessible habitats immediately surrounding the park. Louisianas will breed in woodland swamps and along clean creeks and streams, both of which occur in abundance in these areas. Potential nest sites have been identified from several sources and will be surveyed in May 2010 to determine occupancy and breeding status. This information will improve our knowledge of the local population’s size, demography and habitat preferences. The work will also enable monitoring through comparative analysis in future years.

Nesting hawks & rare woodland butterflies

Hepatica

The search for new MAPS sites to join our existing Maplewood Bog and Rock Ridge stations has begun. The process is challenging, particularly here in the Frontenac Arch where ‘disturbed’ habitats with pronounced edges can be hard to find. The edges are important as this is where adults and young congregate during post-breeding dispersal, which is key to evaluating annual productivity. The heavily forested Frontenac region also tends to feature open understoreys with little shrub or sapling growth – not suitable for capturing birds using mistnets. Therefore the search feels something akin to looking for a needle in a haystack: a daunting job, to be sure, but not impossible. A needle we shall find!

Trout Lilly

Ontario Parks has been a tremendous supporter of FBS and have made a number of useful site suggestions for a second MAPS station within park boundaries. I will be checking out these various sites and will report on them as they are visited. I searched a good candidate site in a small portion of Frontenac Provincial Park today but unfortunately found nothing suitable for a MAPS site. Despite this I did have an incredible outing with some noteworthy discoveries.

Eastern White Pine

Today’s meander took me through a patch of mixed forest dominated by Eastern White Pine. Ruby-crowned Kinglets, Pine Warblers and Yellow-rumped Warblers were numerous in the canopy while newly arrived Eastern Towhees called from small rock outcrops. I came upon this excavation that was recently created by a Pileated Woodpecker, a common inhabitant of Frontenac Park. The sap was running quite thick and apparently attracted and drowned a considerable number of springtails along with a few other insects.

Woodpecker excavation

I spent an hour or two exploring the margins of many small/medium wetlands for good edge habitat but managed to find nothing of any use to a would-be bird bander. I did, however, find an impressive showing of early spring wildflowers such as Trout Lilly, trillium, hepatica, Bloodroot, Dutchman’s Breeches and Spring Beauties. After snapping a few photos, I decided to head for an area of mature forest en route back to the main road.

Red-shouldered Hawk nest

This is when things got interesting! This Red-shouldered Hawk nest was rather easily discovered in a mature Yellow Birch within a steep valley of mature hardwood forest. The adults were nearby and quite displeased with my presence! This is the first nest found by FBS in 2010, which is consistent in habitat and timing with the first nest of 2009 – a Red-shouldered Hawk nest on Canoe Lake Road. I quickly left the nest site to avoid unnecessary disturbance to the hawks, which seemed to be in the beginning stages of nest renovation.

There is a considerable amount of mature deciduous forest in Frontenac with some century old stands present. These forests are ideal for several species of conservation concern such as Cerulean Warbler and Red-shouldered Hawk. However, the ‘real’ biodiversity in these forests is exhibited by its plant and insect communities.

Woodland stream

With forthcoming Louisiana Waterthrush surveys in mind, I ambled down the bank to check on the water level and flow of this stream that courses through the forest. This past winter was the driest in decades and the lack of spring rainfall has further compounded the dry conditions. The result is very low water levels and weak flow of many streams in the park. I am hoping that we will get some decent rain in the coming weeks as the current picture for breeding Louisianas is bleak. There will be more to follow on our efforts to inventory the park’s streams for Louisiana Waterthrush.

West Virginia White at rest (finally!)

The stream valley was hopping with early spring activity and the most apparent of the beasts were these ghostly-white butterflies, which I suspected might be West Virginia Whites (Pieris virginiensis), a species of Special Concern in Canada. An impressive number of these eye catching butterflies were observed fluttering about near the forest floor. This species is known to occur in Frontenac Park where suitable habitats are found. West Virginia Whites occur in mature moist deciduous forests in isolated pockets of southern and central Ontario. They are known to occur at about 50 sites in the province and were once classified as an Endangered Species (1977). The West Virginia White is one of the earliest butterflies to emerge in spring when the adults seek out emerging toothwort, which their larvae feed on exclusively. I will be watching closely for this species during all of the work in mature forest coming up in May.

West Virginia Whites

Often one finds the most interesting things when looking for something else. The search for new MAPS sites will continue……