Effectiveness of direct payments to increase reproductive success of sandbar-nesting river birds in Cambodia

Abstract

SummaryDirect payments to communities or individuals have gained traction as a tool for species conservation; however, few studies have evaluated their effectiveness. From 2010 to 2014, we monitored nests and implemented a direct payment nest protection programme for six sandbar-nesting bird species on the Mekong River, Cambodia, and tested if nest protection improved reproductive success. Nests were guarded by community members; additionally, exclosures were used to protect nests of River Tern Sterna aurantia, the species of highest conservation concern. We investigated factors affecting nest and chick survival, and probability of nest failure due to egg harvest or predation. Nesting later in the season generally resulted in lower nest and chick survival. Nest protection improved survival rates of River Tern nests and chicks, and Small Pratincole Glareola lactea nests. River Tern nest success was 60% for exclosed (and guarded) nests, 29% for guarded (but unexclosed) nests, and 5% for unprotected nests. River Tern fledging success was 82% for exclosed chicks, 40% for chicks that were guarded only, and 2% for unprotected chicks. Small Pratincole nest success was 21% for guarded and 6% for unguarded nests. Egg harvest by humans was lower among protected nests and declined during the study. Nest predation by animals increased during the study despite nest guarding; however, predator exclosures effectively protected nests and chicks. Additional predator control measures could further improve reproductive success of sandbar-nesting birds. Overall, nest protection involving direct payments was highly effective, but required diligent use of nest exclosures, frequent monitoring, and strong community relationships.

Factors influencing nesting success of the river lapwing, Vanellus duvaucelii (Lesson, 1826)

“…The nest survival rates of river lapwings were estimated for the first time in India, although Claassen et al. 19 have calculated nest survival rates in Cambodia. We found that nests of the river lapwing were dispersed in four habitat types, that is, open, unvegetated river bank, open, unvegetated island, vegetated river bank and crop fields.…”

“…At each depredated nest, we recorded potential diagnostic evidence adapted from Fies and Puckett 33 including faeces, hair, the egg remains, nest disturbance and the characteristic tracks of predators such as birds and mammals on the substrate. 11,19 We adapted the approach of Sargeant et al. 34 to identify predators from egg remains.…”

“…17,18 However, the decline in population size of river lapwings was predominantly due to their low reproductive success in Cambodia. 19 The nests are extremely vulnerable to predation by avian and mammalian species and are damaged by flooding due to rainfall and hydropower dam releases or by disturbance from humans and domestic animals. 19,20 Furthermore, exploitation in the form of egg harvesting by local people for their personal consumption has also threatened this species in Cambodia.…”

“…19 The nests are extremely vulnerable to predation by avian and mammalian species and are damaged by flooding due to rainfall and hydropower dam releases or by disturbance from humans and domestic animals. 19,20 Furthermore, exploitation in the form of egg harvesting by local people for their personal consumption has also threatened this species in Cambodia. 11 However, egg harvesting has decreased significantly in recent years due to conservation efforts that have engaged the local people in bird nest protection.…”

“…11 However, egg harvesting has decreased significantly in recent years due to conservation efforts that have engaged the local people in bird nest protection. 19,21…”