Rules of the roost: characteristics of nocturnal communal roosts of rainbow lorikeets (Trichoglossus haematodus, Psittacidae) in an urban environment

Abstract

Rainbow lorikeets (Trichoglossus haematodus) have successfully adapted to urban environments and are today abundant in many Australian cities. Here they often form noisy communal roosts and may damage infrastructure. While extensive studies on problem birds (mainly passeriforms) and their roosts have been conducted in other parts of the world, no detailed studies exist in Australia, where non-passeriform birds (e.g. parrots) can cause problems. This study investigates the roosting preferences of rainbow lorikeets in Sydney (Australia) and establishes the site characteristics that typify these roosts. Lorikeets preferred three exotic tree species, namely the plane tree (Platanus spp. including Platanus x hybrida), Canary Island palm (Phoenix canariensis) and Norfolk Island pine (Araucaria heterophylla). They were also common in brush boxes (Lophostemon confertus), a tree native to Queensland, Australia. Rainbow lorikeets commonly roosted in tall trees with thick trunks and medium density foliage and the trees next to their roost trees were of the same species. Roosting trees were often in areas of high anthropogenic disturbance and close to streetlights.

Guided by the light: Roost choice and behaviour of urban Rainbow Lorikeets (Trichoglossus haematodus)

“…This detailed study found that Rainbow Lorikeets preferred to roost in taller non-native roost trees with thick trunks and confirmed the tendency to use highly disturbed locations that were often close to lights. The roosts investigated in this study were, however, occupied by relatively small numbers of birds, with the largest roosts being classed as ' greater than 20' (Jaggard et al 2015).…”

“…Despite the spectacular growth in urban populations of Rainbow Lorikeets throughout Australia (Fitzsimons et al 2003;Lill 2009), little is known about most aspects of their roosting behaviour. An important exception is a recent study conducted in Sydney, Australia (Jaggard et al 2015). This detailed study found that Rainbow Lorikeets preferred to roost in taller non-native roost trees with thick trunks and confirmed the tendency to use highly disturbed locations that were often close to lights.…”

“…Remarkably, these persistent roosts are often situated in trees in highly developed sites such as the intersections of major roads, shopping centre car parks and adjacent to sporting arenas. Despite high levels of human disturbance, traffic noise and prominent lighting present in these areas, numerous roosts in such areas have been in existence for many years (Jaggard et al 2015). With vast numbers of birds congregating in such sites at nights, concerns and conflicts over noise, soiling and possible health issues are increasing, as are demands for control and management (Temby 2007).…”

Using infrared thermography to detect night-roosting birds

“…, Jaggard et al. ) or have used radio‐telemetry to locate individual birds at roost sites (Jirinec et al. , Leavelle et al.…”

“…Most birds undertake extended bouts of sleep at nocturnal roosts, but few investigators have studied the ecology of bird sleep. Of the few published studies, most have either focused on readily detected communally roosting species (Weatherhead 1983, Dominguez 2003, Smith et al 2008, Gilbert et al 2010, Jaggard et al 2014 or have used radio-telemetry to locate individual birds at roost sites (Jirinec et al 2015, Leavelle et al 2015. Although having some application for single-species studies, radio-tracking can be invasive, time consuming, and costly.…”