the Nest Files – Common Nighthawk

IMG_9621
Common Nighthawk nest contents

j

Although arguably the most studied nightjar in North America, the Common Nighthawk remains poorly known (Poulin et.al. 1996).

h

Species Abstract
Common Nighthawk (Chordeiles minor)

Habitat=primarily nests in open habitats such as rock barrens (also gravel roofs in urban areas)
Area sensitive=?
Average clutch size=2
Nest building period=0 (no nest built)
Incubation period=19 days
Microhabitat=on ground on substrates of either rock, sand, gravel, lichens etc.
Egg colour=variable; creamy white to pale olive gray, heavily speckled with greys, browns and blacks.
Nest site selection=female
Incubation=primarily female
Parasitized by cowbirds=no
k

This Common Nighthawk nest was first discovered at our Rock Ridge MAPS site on June 2, 2009. The female was inadvertently flushed from the nest when traversing one of the countless rocky flats at the site. Incidentally, a Whip-poor-will nest was also discovered on this day, less than 1km from the nighthawk nest. There won’t be many days of nest searching where that happens! Both of these species of the nightjar family have been much in the news of late because of their concurrent and precipitous decline in populations. Common Nighthawk was officially designated as a Species at Risk by COSEWIC in 2007 (Threatened) while Whip-poor-will was just recently recommended for listing in April of this year (Threatened). Nightjars are most active at dawn and dusk and are uniquely adapted to a food source of flying insects such as moths. It is suggested that the presence of a tapeta lucidum, a reflective structure of the choroid part of the eye, aids their vision during low light levels (Nicol and Arnott 1974). Relatively little is known about the breeding ecology and population dynamics of these two species, both of which commonly breed in the Frontenac Arch region of Ontario. Project Whip-poor-will will be starting up soon and will be designed to survey all nightjar populations in the FBS study area.

g

The photo of the “nest” above is typical for Common Nighthawks where the eggs, usually two in a full clutch, are laid directly on the ground without any addition of materials or linings. They will sometime excavate a small scrape to contain the clutch but this activity seems to be determined by the habitat in which they choose to nest. The habitat for nesting nighthawks is quite variable, ranging from gravel rooftops in urban locations to a variety of open habitats adjacent to forests. They frequently inhabit rock barrens as in this particular case but will also nest in recently burned or clearcut forests as well as agricultural fields and grasslands throughout the continent.

g


g
This short video clip was recorded of a defensive adult just after it was flushed off the nest. The Birds of North American account for the species describes defensive behaviour by both sexes as follows:

Male does not directly guard the nest (Dexter 1952) but may dive and boom over nest sites (Rust 1947); in addition, male may defend nest by wing-beating and hissing with mouth wide open (Dexter 1952). Female may use injury-feigning behaviour (fly away, then hiss at intruder) when flushed from eggs or young (Tomkins 1942).

j
I spent no more than three minutes in the vicinity of the nest as I didn’t want to cause any excess amount of distress to the adult tending the eggs. I have a precise fix on its location and will be able to check on its progress at a distance from now on. The photos below provide a longer perspective on the nest site in terms of habitat. I have flushed several of both Common Nighthawk and Whip-poor-will in the area of our Rock Ridge MAPS station since the initial discovery of this nest but have not yet turned up any additional nest sites. The park has a large amount of suitable habitat for Common Nighthawks, perhaps about 1200 hectares worth, which suggests that the species might be common throughout rock barren areas. I will be traveling through much of the barrens starting next week for point count surveys and hope to encounter more of these fascinating birds.
j

IMG_9616
Nest site on rocky slope
IMG_9628
nesting habitat

the Nest Files – Veery

Veery Nest
Veery Nest

Species Abstract
Veery (Catharus fuscescens)

Habitat=Deciduous forest
Area sensitive=yes
Average clutch size=4
Nest building period=6 days
Incubation period=10-14 days
Microhabitat=ground or slightly elevated in shrub/tree
Nest builder=female
Incubation=female
Parasitized by cowbirds=yes

This is the first edition of what will be an ongoing series of nest profiles for breeding bird species of the Frontenac Arch. Searching out and monitoring active nests has always been an important component of ornithology and is also a significant source of data for understanding and tracking changes in demographics and ecology of breeding avifauna all over the world. As part of the Frontenac Breeding Birds program we will be actively searching for nests in select areas to yield valuable information on habitat associations, nest success/failure rates and predation/parasitism rates to name a few. These demographic data combined with vital rate statistics drawn from our three Monitoring Avian Productivity and Survivorship stations will be utilized in concert with standardized population estimates (point counts) to form an integrated approach to avian monitoring.

This Veery nest was discovered on June 6, 2009 at our Maplewood Bog MAPS site. The Veery is one of five members of the Catharus genus of thrushes, which inhabit forests across much of North America. The Veery prefers damp, deciduous forests and tend to favour more successional habitats than the other “spot breasted” thrushes. Nests are built entirely by females in mid-May to early June and are built on or near the ground in 6-10 days (Forbush 1927). This particular nest was found about 8 inches above the ground in the centre of a small juniper in a deciduous woodland clearing. Eggs are laid 4 days after nest completion and the average clutch size is 4 eggs. The female builds the nest alone and incubates the clutch while the male guards the territory until the eggs hatch after 10-14 days after laying. The Brown-headed Cowbird parasitized 19% of nests recorded in Ontario (n=368), making the Veery a sensitive species to habitat fragmentation (Peck and James 1987).

IMG_9585
Veery nest site

I was a bit surprised to find this particular nest in such an “open” spot with full sun shining on the nest and the back of the incubating female. Junipers are definitely a key plant for ground nesting birds in this region as the dense evergreen foliage provides an excellent concealer.

3602404956_faec643147
Female Veery Incubating (S.Leckie)

This incubating female sat very tight to the nest for most of the morning and was only flushed when approached to within 1ft. Luckily, Seabrooke, with camera at hand, was nearby and was able to get a couple of shots of the female tending to the clutch. I was very pleased to find our first Veery nest for Frontenac Bird Studies, as the species’ nest is notoriously difficult to find. We will be on the lookout for more and will also look for nests of its relatives-the Hermit and the Wood Thrush in the coming weeks.

3601590295_3434b00fe8
Veery closeup