Reed Parrotbill nest predation by tidal mudflat crabs: Evidence for an ecological trap?

Abstract

Abstract. Understanding the relationships between nesting habitat quality and predation risk is essential for developing appropriate conservation management for threatened species. This is particularly relevant where anthropogenic pressures could decouple the environmental cues used by birds to assess nesting habitat quality from increased predation risk. In this study, we conducted a series of surveys and nest experiments to examine the nest predation rates of Reed Parrotbill (Paradoxornis heudei ) a passerine bird between inland and tidal reed-bed wetland habitats, at Yellow River Delta National Nature Reserve, Eastern China during 2008, and 2010-2012. We found significant differences in the habitat structural characteristics between the two adjacent wetland habitats that are critical for Reed Parrotbill nest-site selection. Experimental trials using recently constructed and abandoned Reed Parrotbill nests as 'artificial nests, quail eggs and predator-exclusion measures, revealed that tidal mudflat crab (Helice tientsinensis) was the primary cause of Reed Parrotbill egg predation in tidal reed-bed habitat. Annual predation rates of real nests from inland reed-bed habitat varied from 35% to 68%, and predation rates of artificial nests were much lower than those from real nests. Pitfall sampling revealed that the abundance of tidal mudflat crabs was significantly higher in tidal reed-bed habitat. Our data suggested that Reed Parrotbills breeding in tidal reed-bed habitats may be highly vulnerable due to extremely high rates of nest predation (up to 100%), caused primarily by the high density of tidal mudflat crabs. The incongruence between nest-site habitat preference and nest survival indicated an ecological trap scenario, which requires further studies on its proximate and ultimate causes as well as the development of effective conservation management for the Reed Parrotbill.

Explaining variation in brood parasitism rates between potential host species with similar habitat requirements

“…We carried out the fieldwork from May to August in 2008 (parrotbills only) and in 2010-2012 (warblers and parrotbills) in the YRD National Nature Reserve (37°35′−38°12′ N, 118°33′−119°20′ E), Shandong, Eastern China. The study area is located in the second largest estuarine wetland area of China and contains extensive reed habitats, interspersed with stretches of black locust Robinia pseudoacacia forests and farmlands (see Li et al 2015a for more details). Warblers are recognized as the main hosts of the cuckoo in lowland reed habitats of Eastern Asia (Yang et al 2012(Yang et al , 2014.…”

Mammalian predators and vegetated nesting habitat drive reduced protected area nesting success of Kentish plovers, Yellow Sea region, China

“…The high levels of predation by mammals within the PA, despite optimal nest site selection, may also represent an ecological trap for the plovers (Donovan & Thompson, 2001). This is, in fact, not uncommon in many other protected area ecosystems (Li et al, 2015), and disentangling the drivers of this potential ecological trap, such as the high nest predation rate by mammals within the protected area, would be a crucial first step to improve PA conservation management further. In the recently restored sparse vegetated and bare land that was sampled for this study, we have only found fewer than 10 nests of Saunders's gulls and other tern species within the colony of Kentish plovers, which perhaps implies that there were fewer benefits from any collective defense by these species against mammal predators.…”

Are oil and natural gas development sites ecological traps for nesting killdeer?

“…Several studies have demonstrated the consequences of ecological traps for species conservation within modified habitat (e.g. agricultural fields, airports, reservoirs and urban areas (Gates and Gysel 1978, Best 1986, Marini et al 1995, Li et al 2015). Yet oil wells have received relatively less attention as a potential ecological trap for wild species in disturbed landscapes (Ludlow and Davis 2018).…”