Vigilance and Activity Time-Budget Adjustments of Wintering Hooded Cranes, Grus monacha, in Human-Dominated Foraging Habitats

Abstract

Due to loss and degradation of natural wetlands, waterbirds increasingly rely on surrounding human-dominated habitats to obtain food. Quantifying vigilance patterns, investigating the trade-off among various activities, and examining the underlying mechanisms will help us understand how waterbirds adapt to human-caused disturbances. During two successive winters (November-February of 2012–13 and 2013–14), we studied the hooded crane, Grus monacha, in the Shengjin Lake National Nature Reserve (NNR), China, to investigate how the species responds to human disturbances through vigilance and activity time-budget adjustments. Our results showed striking differences in the behavior of the cranes when foraging in the highly disturbed rice paddy fields found in the buffer zone compared with the degraded natural wetlands in the core area of the NNR. Time spent vigilant decreased with flock size and cranes spent more time vigilant in the human-dominated buffer zone. In the rice paddy fields, the birds were more vigilant but also fed more at the expense of locomotion and maintenance activities. Adult cranes spent more time vigilant and foraged less than juveniles. We recommend habitat recovery in natural wetlands and community co-management in the surrounding human-dominated landscape for conservation of the hooded crane and, generally, for the vast numbers of migratory waterbirds wintering in the middle and lower reaches of the Yangtze River floodplain.

Shifts in foraging behavior of wintering Hooded Cranes (Grus monacha) in three different habitats at Shengjin Lake, China

“…Under the conditions of wetland degradation and habitat loss, waterbirds are forced to feed in areas severely disturbed by humans. As well, they need to increase their vigilance and reduce foraging time to ensure more secure access to food (Li et al 2015).…”

“…During the autumn and winter drawdown, mudflats are exposed and the waterbirds feed on Anodonta woodiana (Zhang and Lu 1999;Fox et al 2008). As a consequence of wetland degradation and habitat loss, the carrying capacity of these wetlands has decreased and the traditional food sources of these wintering waterbirds have experienced a sharp decline in quantity (Li et al 2015). The cranes have shifted habitat from mudflats to farmland, such as harvested paddy fields with rice grains, to look for supplementary sources of food (Yang et al 2015).…”

Wood mice aggressiveness and flight response to human handling: Effect of individual and environmental factors

“…Several measures for evaluating human‐caused effects on wild populations have been used (Tarlow & Blumstein, ), but behavioural changes have been often considered the most sensitive measure of animal′s susceptibity to human effects. In general, human disturbance has been demonstrated to incur opportunity costs on animals mainly by causing increased vigilance, flight, avoidance of areas, changes in habitat use and reduced foraging activity (Filla et al., ; Jayakody, Sibbald, Gordon, & Lambin, ; Li, Zhou, Xu, Zhao, & Beauchamp, ; Lord, Waas, & Innes, ; Parsons et al., ; Richard & Côté, ; Tablado & Jenni, ), although the type and threshold of the behavioural responses vary in relation to human, environmental and species‐specific factors (Tablado & Jenni, ). According to previous research, these behavioural decisions made by animals responding to human presence and/or activities suggest that wildlife may perceive humans as a potential threat similar to predation risk (Beale & Monaghan, ; Frid & Dill, ; McLean, Smith, & Stewart, ; Walther, ).…”

TIME-OF-DAY BUT NOT SEASONALITY INFLUENCES FEEDING AND DIURNAL TIME ACTIVITY BUDGET OF ADULT RED-CAPPED LARK (Calandrella cinerea).

“…In the White-breasted Kingfisher Halcyon smyrnensi, studied at Cauvery Delta Region (India), the two activities allocated the highest proportion of activity budget was scanning (54% of time) and feeding (23% of time), with less time allocated to flying (13% of time), preening (6 %) and resting (4% of time). In the Hooded crane (Grus monacha) studied at Shengjin Lake National Nature Reserve in China, activities that were confirmed to be most common in the time-budget were feeding, scanning and movements, with feeding and scanning accounting for more than 70 % of the total time budget (Li et al, 2015). The dominance of these activities in the time activity budget of the Red-capped Lark like in other avian species is possibly an indication of their importance in complementing success in feeding activities and reducing the risk of predation.…”

“…The mean scan rates for the Red-capped Lark did not vary significantly between seasons, possibly due to ground foraging and nature of its open grassland habitat that may require birds to consistently remain vigilant to avoid predation. Furthermore, this may also be attributed to the possibility that insect food density did not vary significantly between seasons since levels of vigilance may vary with changes in food density (Li et al, 2015). Given that the Red-capped Lark inhabits an open grassland area that may expose it to high temperatures especially when dry, resting activity observed (often under grass tufts and forbs) especially during mid-hours of the day most likely aimed at avoiding increased temperatures and allowed dissipation of heat load (Nilsson et al, 2016).…”