Population, distribution, habitat use and breeding of Gurney's Pitta Pitta gurneyi in Myanmar and Thailand

Abstract

SummaryGurney's Pitta Pitta gurneyi was not seen in the wild for over 30 years before its rediscovery in a small area in southern Thailand in 1986. In 2003, it was found over a much larger area in southern Myanmar (Burma) after an even longer absence of records. This paper reports the results of recent research on both populations. In Myanmar, birds were found in a high proportion of visited sites, including sites up to 40 km further north than any previous records in the country. Occupied forest sites had a higher density of seedlings, saplings, bamboo and rattan than unoccupied forest sites, suggesting a preference for regenerating forest. There was no evidence of a decline in the species's likelihood of occurrence up to at least the highest visited altitude of 230 m. Maximum entropy models suggested a potential range size of between 3,200 and 5,800 km 2 and the predicted range extended just over the border into Thailand, suggesting that birds might persist there. Population estimates for southern Myanmar ranged from 9,300 to 35,000 territories, with a mid-point estimate of 20,000 territories, based upon range sizes modelled from different parameters and a range of territory densities estimated from Thailand. The population in southern Thailand was estimated at between 15 and 20 territories in 2003, 2005 and 2007, and there was a reduction in the historic rate of forest loss in the core range over the same period, suggesting that long-term declines have been at least temporarily contained by recent conservation intervention. However, nesting success in Thailand was very low, due to heavy nest predation by cat snakes Boiga. Nests were usually built close to waterlogged areas and damp gullies, and nestlings were fed almost exclusively on earthworms. Occupied sites in Thailand had a higher density of seedlings, saplings, spiny palms and rattans, but sparser ground cover and a lower density of large trees and bamboo, than forests in Myanmar, indicating their secondary nature. Occupied and unoccupied sites in Myanmar were structurally more similar to each other than either was to occupied sites in Thailand. The results suggest that the species might inhabit a wider range of altitudes, slopes and forest types than previously thought, and so might persist in previously unsurveyed areas and might survive or even benefit from a degree of forest disturbance. However, the species's conservation-dependent status in Thailand and accelerating forest clearance in Myanmar suggest that forest protection measures are urgently needed to secure its long-term future.

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“…Black-crowned Pitta nestlings might require less food if they receive a higher quality diet (Twining et al 2016) or have a longer nestling period (but see Nestling development and fledging). Our observations of nestling diet appear typical of many pittas (Round et al 1989, Lin et al 2007b, Donald et al 2009, Kim et al 2012). This is not necessarily indicative of nutritional content, though, especially because we have no measure of how prominently earthworms figured in diet relative to other invertebrates.…”

“…This classification is supported by morphology and occurrence of sexual dimorphism (Irestedt et al 2006), but further comparisons are difficult because data on much of the pittas' natural history are lacking. Only the breeding biology of Gurney's Hydrornis gurneyi, Giant H. caerulea, Rainbow Pitta iris and Fairy Pittas P. nympha have been fully documented (Round & Treesucon 1986, Round et al 1989, Gretton 1988in Lambert & Woodcock 1996, Zimmermann & Noske 2003, Lin et al 2007b, Donald et al 2009, Kim et al 2012, while sporadic quantitative data have been reported for a handful of other species (Lambert & Woodcock 1996, Erritzoe & Erritzoe 1998. The nests and clutch sizes of most Erythropitta are known, but virtually no detailed observations have been made on the nesting behaviour of any species in this genus.…”

Nest predators of southeast Asian evergreen forest birds identified through continuous video recording

“…Snakes were the second most prevalent predator in each year of our study. Nocturnal nest predation by cat snakes has also been recorded in southern Thailand (Donald et al 2009). In one of the few studies to use videography to monitor nest predation, diurnal snakes were found to be the most prevalent predator (Robinson et al 2005).…”

Poor overlap between the distribution of Protected Areas and globally threatened birds in Africa

“…Approaches vary in precision, from species-specific models (e.g. Osborne, Alonso & Bryant, 2001;Donald et al, 2009) to the use of broad habitat associations for species and general land cover maps (e.g. Rondinini et al, 2005;Buchanan et al, 2008).…”