Rapid Nestling Mortality in Arctic Peregrine Falcons due to the Biting Effects of Black Flies

Abstract

ABSTRACT. This note describes nestling mortality in Arctic Peregrine Falcons (Falco peregrinus tundrius) due to the biting effects of blood-feeding black flies (Diptera: Simuliidae). At a nest site near Rankin Inlet, Nunavut, Canada (62˚49′ N, 92˚05′ W), a brood of four nestlings died on 20 July 2013 from the direct effects of severe bites attributed to black flies. Within three hours of the onset of blood-feeding, black flies had caused widespread, uniformly distributed hemorrhagic coalescent lesions over the head and body of all nestlings. Approximately seven hours after the first flies appeared, the female falcon removed the carcasses of the dead nestlings from the nest. Nestlings at eight additional sites also suffered the effects of biting black flies in 2013, resulting in the deaths of 13 of 35 nestlings. A less pronounced outbreak also occurred in 2012 and resulted in the deaths of seven nestlings at four sites. No nestling mortality due to black flies has been documented in any other year from 1982 through 2015. To our knowledge, these observations document the northernmost lethal attack by ornithophilic black flies in North America.Key words: Arctic; avian; climate change; black fly; mortality; Peregrine Falcon; Simuliidae RÉSUMÉ. Cet article décrit des événements de mortalité d'oisillons chez le faucon pèlerin (Falco peregrinus tundrius) causés par des morsures de mouches noires hématophages (Diptera : Simuliidae). À un site de nidification près de Rankin Inlet, Nunavut, Canada (62˚49′ N, 92˚05′ O), les quatre oisillons d'une couvée sont morts le 20 juillet 2013 des effets directs de morsures sévères attribuables aux mouches noires. Dans les trois heures suivant le début de l'activité des hématophages, les mouches noires avaient causé des lésions hémorragiques et coalescentes uniformément distribuées sur la tête et le corps des oisillons. Environ sept heures après l'apparition des premières mouches, la femelle a retiré les carcasses des oisillons morts du nid. Des oisillons à huit autres sites de nidification ont également subi les effets des mouches noires hématophages en 2013, entraînant la mortalité de 13 oisillons sur un total de 35. Une émergence moins prononcée s'est aussi produite en 2012 et a causé la mort de sept oisillons à quatre sites de nidification. Aucune mortalité d'oisillons causée par les mouches noires n'a été documentée de 1982 à 2015. À notre connaissance, ces observations documentent les attaques létales par les mouches noires ornithophiles les plus nordiques en Amérique du Nord.

Precipitation and ectoparasitism reduce reproductive success in an arctic-nesting top-predator

“…High exposure and sensitivity without any particular high adaptive capacity 29 make arctic vertebrates particularly vulnerable to parasites 12 , 19 and extreme weather events 3 , 30 . Our results confirm that increased frequency of heavy precipitation can reduce reproductive output of arctic-nesting peregrine falcons directly (through exposure to cold, wet weather), and indirectly through the outbreak of black flies described here and elsewhere 31 . We qualitatively summarized the frequency and severity of these effects on the reproduction of arctic-nesting peregrine falcon during major phases of the breeding cycle (Fig.…”

“…Precipitation during the pre-laying period likely triggers the hydrological conditions 33 and nutrient runoff levels 32 required for black fly reproduction. This ultimately results in indirect nestling mortality once adult black flies emerged (this study) and begin blood feeding (i.e., the proximate cause of mortality) on nestlings 31 . During incubation, precipitation directly reduces egg survival (Franke, unpublished data).…”

“…The species of black fly ( Metacnephia saskatchewana ) likely responsible for mortality of nestlings in 2013 had not been reported in Rankin Inlet prior to 2016 31 . However, other ornithophilic species have been reported in Rankin Inlet ( Simulium silvestre ) and other nearby communities; ( Simulium anatinum and Simulium annulus at Arviat and Baker Lake, Nunavut, Canada) 27 .…”

“…2 ) is more likely driving the observed low nestling survival that year while in 2012, a combination of heavy rain and black fly outbreak are responsible for the low reproductive success. During the outbreaks, the biting effect of black flies resulted in widespread mortality due to the effects hemorrhagic coalescent lesions on the head and body of affected nestlings 31 .…”

Common Loons respond adaptively to a black fly that reduces nesting success

“…Owing to their occasional massive outbreaks and tendency to feed on humans and domestic animals, black flies have caused negative economic impacts on forestry, tourism, and agriculture (Adler and McCreadie 1997). Attacks of black flies have been shown to compromise the breeding efforts of avian breeding pairs through their attacks on adults (Urbanek et al 2010, Solheim et al 2013) and young (Hunter et al 1997, Smith et al 1998, Franke et al 2016). However, no study has yet demonstrated an impact of black flies on a natural avian population (Adler et al 2004).…”