{"id":3410,"date":"2020-10-09T00:20:19","date_gmt":"2020-10-09T00:20:19","guid":{"rendered":"http:\/\/wordpress.viu.ca\/biol325\/?p=3410"},"modified":"2020-10-09T00:20:21","modified_gmt":"2020-10-09T00:20:21","slug":"the-dark-eyed-junco-the-innocent-burglar","status":"publish","type":"post","link":"https:\/\/wordpress.viu.ca\/biol325\/2020\/10\/09\/the-dark-eyed-junco-the-innocent-burglar\/","title":{"rendered":"The Dark-Eyed Junco: The Innocent Burglar"},"content":{"rendered":"\n

Part 1: Introduction to the Dark-Eyed Junco<\/h2>\n\n\n\n

DESCRIPTION AND IDENTIFICATION<\/p>\n\n\n\n

The Dark-eyed Junco (Junco <\/em>hyemalis) is one of the most abundant birds in North America (Bailey et al., 2017<\/a>) with recent estimates suggesting the entire population is somewhere around 630 million individuals (The Cornell Lab of Ornithology, 2019<\/a>). This passerine (order Passeriformes) is part of the family Passerellidae also known as the New World Sparrows (The Cornell Lab of Ornithology, 2019<\/a>).  Often recognized by its burglar-like appearance here in BC due to its conspicuous black hood, the colouration of Dark-eyed Juncos actually varies greatly with geographical location; so much so that 5 out of the 6 recognized forms were considered different species until the 1980s (Cornell Lab of Ornithology, 2019<\/a>). Although the plumage pattern of juncos differs depending on their location, juncos are generally dark-grey or brown in colour. Despite this variation in plumage, it is easy to identify a junco based on their flashy white outer tail feathers that are easily spotted while they\u2019re in flight (McGlothlin et al., 2007<\/a>), as well as their light pink bill.<\/p>\n\n\n\n

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Figure 1: The different variations of Dark-eyed Junco plumage across North America (photos by Scott Martin<\/a>, Sam Hough, Chris Wood, Amanda Guercia, Michael Todd and Brad Heath)<\/figcaption><\/figure>\n<\/div><\/div>\n\n\n\n

If you were to take a walk through the woods at this time of year, you would likely hear the soft chirps of local Dark-eyed Juncos as they wander through the brush, possibly trying to encourage other juncos to follow. <\/p>\n\n\n\n

Male juncos across the different subspecies typically have repertoires of 2-8 song types, and are often slightly improvised or modified by the individual (Reichard, 2014<\/a>). During breeding season, male juncos don\u2019t rely solely on their plumage to attract and stimulate potential mates, songs play an important role in mate selection. The advertising song of a junco is usually a single trill, consisting of a single pitch (Audubon, 2019<\/a>).<\/p>\n\n\n\n

Call of the Oregon Dark-eyed Junco: note the single trill (audio from Darin JM<\/a>)<\/figcaption><\/figure>\n\n\n\n

Certain calls given by the dominant male junco are used as aggressive warnings for other male juncos to essentially \u201cback off\u201d (The Cornell Lab of Ornithology, 2019<\/a>). Some studies have shown that despite similarities between the 6 recognized subspecies\u2019 calls, male juncos actually respond more aggressively to the trills of other local males rather than an almost identical call from a junco of a different geographical location (Reichard, 2014<\/a>).<\/p>\n\n\n\n

DISTRIBUTION<\/p>\n\n\n\n

With a rapid radiation through North America since the last glaciation (Reichard, 2014<\/a>), dark-eyed juncos are found in nearly every corner of the continent, from Alaska to Mexico and BC to Nova Scotia.<\/p>\n\n\n\n

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Figure 2: Range distribution of Dark-eyed Juncos throughout North America showing areas occupied during Breeding, Non-breeding and Year-round (photo by The Cornell Lab of Ornithology<\/a>)<\/figcaption><\/figure>\n\n\n\n

Fondly called the \u201coriginal snowbirds of middle latitudes,\u201d many Dark-eyed Juncos in the US leave the mountains in which they inhabit throughout the breeding season for a slightly milder winter in the Eastern United States (Audubon, 2018<\/a>). Some juncos do stay year-round, while others just over-winter.<\/p>\n\n\n\n

HABITAT AND NESTING LOCATION<\/p>\n\n\n\n

No one has ever accused the Dark-eyed Junco of being overly picky about its habitat. This is likely because juncos can be found inhabiting coniferous forests (pine, Douglas-fir, spruce, and fir), deciduous forests (aspen, cottonwood, oak, maple, and hickory), open woodlands, fields, parks, gardens and even roadsides all throughout North America (The Cornell Lab of Ornithology, 2019<\/a>).<\/p>\n\n\n\n

This lack of fuss over habitat carries over into their selection of nest sites as well. Typically, juncos are ground-nesting birds (among roots, in rock crevices, at the base of vegetation, etc.) but they can also nest in taller vegetation such as trees, and even man-made structures such as buildings, window ledges, planter boxes and even hanging flower baskets (Bailey et al., 2017<\/a>).<\/p>\n\n\n\n