Fr: Moucherolle à côtés olive
    Ang: Olive-sided Flycatcher
    All: Olivflanken-Schnäppertyrann
    Esp: Pibí Boreal
    Ita: Pigliamosche fianchioliva
    Nd: Sparrenpiewie
    Sd: nordlig pivi
Photographers:
Roger Ahlman
    Pbase Galleries Peru and Ecuador 
Tom Grey
  Tom Grey's Bird Pictures & Tom Grey's Bird  Pictures 2 
Text by Nicole Bouglouan
Sources:
HANDBOOK OF THE BIRDS OF THE WORLD Vol 9 - by Josep del Hoyo - Andrew Elliot - David Christie - Lynx Edicions - ISBN: 8487334695
BIRDS OF THE GREAT BASIN – by Fred A. Ryser, Jr - University of Nevada Press -ISBN: 0874170796
South Dakota Birds and Birding – (Terry L. Sohl)
Bird Web (Seattle Audubon Society)
The Northwest Territories (NWT) Species at Risk
Olive-sided Flycatcher Migration & Breeding
What Bird-The ultimate Bird Guide (Mitchell Waite)
Wikipedia, the free encyclopaedia
Olive-sided Flycatcher 
      Contopus cooperi
Passeriformes Order – Tyrannidae Family
INTRODUCTION:
    The  Olive-sided Flycatcher breeds in coniferous forest of North America, from N  Alaska across Canada, with extensions southwards into the USA. This  long-distance migrant spends the winter in Central America and a large northern  part of South America.   
    It is a  compact, big-headed flycatcher often seen perched upright on high branch in  tree while singing. If feeds mainly on insects caught by sallying and returning  to the same perch. The male performs aerial displays at the beginning of the  breeding season. The cup-shaped nest is built in tree, mainly in conifer. 
    The  Olive-sided Flycatcher is threatened by loss and degradation of the forest  habitat on both breeding and wintering grounds, but also during migration. 
    The  species is currently listed as Near Threatened. 

DESCRIPTION OF THE BIRD: 
      Biometrics:
    Length:  18-20 cm
    Wingspan:  33 cm
    Weight:  29-35 g
The  Olive-sided Flycatcher has deep olive-grey to brownish-olive head and  upperparts. The upperwing is dusky with indistinct greyish wingbar. Inner  secondary and tertial flight-feathers have whitish edges. There is a white tuft  on each side of the rump, often hidden by the wing. The tail is dusky.
    The  underparts, throat, breast and belly are dull white to yellowish, whereas body  sides and flanks are streaked/mottled dusky olive, giving the bird the  appearance of wearing an unbuttoned vest (Altman & Sallabanks). The  undertail-coverts show dull, brownish-grey feather centres. 


The head  is like the upperparts with a peaked crest (sometimes flattened). 
    The  broad, two-tone bill has black upper mandible and yellow/pale orange lower  mandible with dark tip. The eyes are dark brown. Legs and feet are black.  
Male and  female are similar. 
    The  juvenile resembles adult but it is browner overall. Wingbars and edges of  tertials are washed buff. 
DISTRIBUTION GEOGRAPHIQUE:      
    The  Olive-sided Flycatcher breeds from N and W Alaska, E across C Canada to Maritime  Provinces, and also S in the USA to N California, locally into NW Mexico (Baja  California). In the interior, it breeds through Idaho and W Montana to NE  Arizona, NW New Mexico and W Texas. In the E, it breeds to the boreal regions  of Adirondacks and New England, S to Appalachian Mountains. 
    It moves  over long distances to spend the winter locally in W and S Mexico, S to Panama  and from Colombia and Venezuela, S to SE Peru and NW Bolivia, and also in  Ecuador. It can be found locally in the Guianas, S Amazonia and SE Brazil. 

HABITAT:   
    The  Olive-sided Flycatcher breeds mainly in openings and edges of coniferous  forests. It has adapted to logging and fires if snags and residual trees remain  to provide perches and foraging places. It also occurs at high densities in  burned areas in inland pine forests. The species also breeds in moist, coastal  forests, along streams and shorelines where it finds numerous insects. In the  boreal zone, it also frequents bogs and swamps. It breeds from sea-level to  3,350 metres of elevation. 
    On  migration, it frequents riparian and non-coniferous habitats, mainly in  mountains. 
    During  winter, it is present in evergreen forest at mid-elevation, especially in  openings and edges where snags are present, between 400 and 3,400 metres. 

CALLS AND SONGS: SOUNDS  BY XENO-CANTO 
    The  Olive-sided Flycatcher’s call is a “pip,pip,pip” or “bik,bik,bik” including  three spaced hard notes. This call is given by both male and female all year  round. Near the nest, both mates give twittering “pip”-like notes. The male  also utters a short song-call combination “peer-pip”, and we can hear a squeaky  “eek” during attacks against predators. They also perform bill-snapping. 
The song  is given from very high perches, and mainly early in the morning and in the  evening. There are three syllables in the song. The first syllable is short,  sharp and not very loud, whereas the two following syllables are loud and  strongly accented. This penetrating whistle is described as “whit, whee-pew” or  “whip wéédééér” also known as  “quick, three beers”. This readily identifiable bird song makes this species a  favorite of birders.
    However, the  calls of the Pacific birds vary slightly “what peeved yoou” with no syllable  emphasized.    

BEHAVIOUR IN THE WILD:     
    The  Olive-sided Flycatcher feeds mainly on flying insects and especially bees and  wasps, but also ants, flies, moths, grasshoppers, dragonflies and beetles.
    It  typically hunts like all Tyrannidae by waiting quietly from exposed  perches and sallying out to catch the prey in the air, before to return to the  same perch. The small prey are eaten in flight, but the larger items are  carried back to the perch and sometimes hit against the perch before to consume  them.  
    In  Alaska, birds foraging near the ground are reported.  


During the breeding season, the male defends the territory by singing  continuously. The courtship displays are poorly known, but they probably  involve active chasings through the treetops. 
    But some observations describe interesting flight displays. 
    In the first display, two birds (sexes unknown) engaged in a mutual  pendulum display while performing bill-snapping. The two birds flew back and forth  in an arc parallel to each other. This flight was repeated 3-4 times before going  to two different perches. This display was repeated several times, between 14  and 17 metres above the ground. 
The Olive-sided Flycatcher is a long-distance migrant. The birds  breeding in Alaska perform a remarkable 20,500 annual journey, with adults wintering  as far as Bolivia. They migrate at night. 
    They leave the breeding grounds between early August and early September  and arrive in South America in October/November. They leave the wintering  grounds in late March/April and arrive on their breeding grounds from April to  late May.
The Olive-sided Flycatcher has swift, direct flight with rapid wingbeats.

REPRODUCTION OF THIS SPECIES:  
    The breeding  season takes place between May and August. 
    The female  builds a cup-shaped nest, usually placed towards the tip of horizontal branch  well out from the trunk in conifer, although deciduous trees are also used depending  on the range. The nest is made with twigs, grass and weeds, and the cup is  lined with lichen, grass and pine needles.  
The female lays 3-4 pinkish-buff eggs with brown and grey spots. She incubates alone during 14-17 days. Both parents feed the chicks that fledge between 15 and 23 days after hatching, with the first flight at about 21-23 days of age.
PROTECTION / THREATS / STATUS:    
    The  Olive-sided Flycatcher is threatened by degradation and loss of the habitat  caused by human activities, involving reduction of food sources and increasing  numbers of predators. However, the species is able to adapt to several types of  harvested forest, fairly similar to its preferred post-forest fire habitat mosaics. 
    On the  wintering grounds, the tropical deforestation has also a negative impact. 
    The population  of this species has undergone a significant decrease over the last 40 years in  North America. 
    Currently,  the Olive-sided Flycatcher is listed as Near Threatened.  
