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

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.

The protozoan parasite Trichomonas gallinae causes adult and nestling mortality in a declining population of European Turtle Doves, Streptopelia turtur

SUMMARYStudies incorporating the ecology of clinical and sub-clinical disease in wild populations of conservation concern are rare. Here we examine sub-clinical infection by Trichomonas gallinae in a declining population of free-living European Turtle Doves and suggest caseous lesions cause mortality in adults and nestlings through subsequent starvation and/or suffocation. We found a 100% infection rate by T. gallinae in adult and nestling Turtle Doves (n = 25) and observed clinical signs in three adults and four nestlings (28%). Adults with clinical signs displayed no differences in any skeletal measures of size but had a mean 3·7% reduction in wing length, with no overlap compared to those without clinical signs. We also identified T. gallinae as the suggested cause of mortality in one Red-legged Partridge although disease presentation was different. A minimum of four strains of T. gallinae, characterized at the ITS/5·8S/ITS2 ribosomal region, were isolated from Turtle Doves. However, all birds with clinical signs (Turtle Doves and the Red-legged Partridge) carried a single strain of T. gallinae, suggesting that parasite spill over between Columbidae and Galliformes is a possibility that should be further investigated. Overall, we highlight the importance of monitoring populations for sub-clinical infection rather than just clinical disease.

Breeding behaviour and breeding success of feral pigeons in the Bloemfontein urban area

Breeding activities of feral pigeons (Columba livia) in the Bloemfontein urban area occur throughout the year with a decrease during the late summer months when seasonal rainfall in the region reaches a peak. Nest construction is relatively primitive and is characterised by a loose composition of nesting material on accumulated dry bird droppings. Two eggs represent the most common clutch size and eggs are usually laid within two days of each other. Both parents are involved in the incubation process lasting more than two weeks, during which the eggs undergo a progressive decrease in mass. Recently hatched nestlings are covered in yellow down and are largely helpless. True feathers only start to emerge after the first week, and from the third week individuals can move about unsteadily. Apart from the first number of days after hatching, nestlings of rare single egg clutches constantly maintain a body mass lower than those from an average clutch. The overall success of 247 breeding pairs for this study was 34%. Egg loss is higher than the mortality rate of nestlings, and is mainly affected by climatic factors such as rainfall. Predation appears to be the most important factor influencing nestling mortality. Aggressive interactions between speckled pigeons and rock doves, however, as well as possible intraspecific aggression also play a significant role.