Nest-site selection by Purple Swamphen in Haifeng, China

Introduction

The Blue-eared Pheasant (Crossoptilon auritum), related to the Galliformes, Phasianidae, is a rare but important bird, endemic to China. This bird is found only in the mountainous regions of Qinghai, Gansu and Sichuan provinces and the Ningxia Hui Autonomous Region (Lu and Zheng, 1998). It is listed as a 'vulnerable bird' in the China Red Data Book of Endangered Animals (RDB -AVES, 1996) (Zheng and Wang, 1998) and it is also ranked as a second grade key protected wildlife species in China since it is experiencing a drastic population decline.

Morphologically, the Blue-eared Pheasant can be distinguished easily from other Crossoptilon species by its distinctive blue feathers. Males and females are similar except for spurs on the legs of the males above their hind toe. The top of the head is covered with black feathers, with greatly elongated white ear-coverts. The Blue-eared Pheasant has no subspecies differentiation and is a typical, high elevation, cold forest bird. Some information on its biology has been reported in recent years (Liu et al., 2005; Sun et al., 2005; Wu and Liu, 2010a, 2010b, 2011). In light of this, we provide updated information on the ecology and conservation status of the Blue-eared Pheasant, by integrating published data with our field surveys in the Gaihai-zecha National Nature Reserve, in the south of Gansu Province, from 2006 to 2008.

Habitat

In Helan Mountain, Ningxia, the Blue-eared Pheasant in winter prefers conifer forests dominated by Pinus tabulaeformis and Picea crassifolia and avoids other vegetation types. This pheasant shows a strong preference for sunny and shady slope aspects and avoids half sunny and half shady slopes. Compared with random plots, the sites used are characterized by dense vegetation of trees and shrubs, steep slopes, closed covers for hiding, shallow snow depths and high elevations. Hiding cover, tree and shrub densities, distance to water sources and slope angles are critical factors in discriminating between usage sites and random plots (Liu et al., 2005). In the forests of south Gansu, the principal foraging method for field flocks of Blue-eared Pheasants in winter consists of digging up plant roots. It is difficult for birds in tall trees and grass cover to dig for food on frozen ground, given the weak solar radiation in coniferous forests. Therefore, these flocks prefer habitats with scattered trees and grasses during the non-breeding stage (Wu and Liu, unpublished data).

In the breeding stage, the Blue-eared Pheasant in the Gaihai-zecha Reserve prefers steep slopes (average 43.36 ± 13.95°) for foraging (Fig. 1), which is similar to that of the Golden Pheasant (Chrysolophus pictus) with slope angles ranging from 30° to 50° (Shao, 1998). The disturbance by collecting potherbs and herding in local forests has affected the available area for this pheasant, which can be verified by the variation in the distances to paths between the breeding habitats and control site of this pheasant. Our study also revealed that breeding Blue-eared Pheasants prefer mid-high and high positions on slopes with greater species richness and higher cover of grass, because in these areas these conditions not only provide the seeds and roots of grasses for foraging but are also good places for finding different kinds of insects (Wu and Liu, unpublished data).

Figure  1.  Habitat of Blue-eared Pheasant in Gaihai-zecha National Nature Reserve, Gansu, China (Photo by Yiqun WU)

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Activity time and rhythm

In Pingwu County of Sichuan, the active time of the Blue-eared Pheasant is just 4 h per day in the winter. In the spring, its active time gradually extends and reaches 6 h. In summer and autumn, most Crossoptilon auritum activities are concentrated in the periods from 6:00–10:00 and 15:00–20:00 (Li et al., 1985). In Jianza County of Qinghai, this pheasant starts its activities at approximately 9:30-10:00 and its all-day activity time reaches 7–8 h in the winter. Spring activities begin at 7:00–8:00 and the total active period is 10 h. The longest activity time is in the summer and can last up to 12 h (Zheng and Liao, 1983). In the Qilian forests of Qinghai, the active time shows two peaks, i.e, from 9:00 to 12:00 and from 15:00 to 19:00 in the summer; there is only one active time in the winter, i.e., from 12:00–16:00 (Li and Li, 1981).

We studied the diurnal behavior of Crossoptilon auritum by scan sampling in the Zecha forest, Gansu. From our day-time observations in the winter, we conclude that the adult Blued-eared Pheasant spends much time in feeding (40.62%), followed by resting (28.01%), moving (19.17%) and guarding (12.55%). Given the time budget of breeding pairs, the proportion of time spent on feeding by males was 34.39 ± 1.83% and guarding 29.62 ± 1.93%. For females, feeding accounted for 53.23 ± 2.19% of the time. From this mutual behavior, it is seen that males devote more time on guarding than females, but males spend less time on feeding and other types of behavior than females. However, there were no significantly differences between males and females in time spent on moving, resting and standing (Wu and Liu, 2010a).

Nest-site features

In the Wanglang Reserve of Pingwu County in Sichuan, Blue-eared Pheasants prefer to built their nests in willow groves or birch forests on sunny slopes, which are hidden in Cotoneaster microphyllus, sedges and piles of tree branches (Li et al., 1985). The nest is like a disk, simple and crude. At times, hay, leaves and their own abdominal feathers can be found in the nest of this pheasant, which can provide a cover against rain and forms a windbreak in order to maintain the temperature of the nest (Liao, 1984).

Nest sizes vary slightly in different habitats. In the Qilian forest region of Qinghai, the average nest diameter was (36–38) cm × (27–28) cm (n = 2) (Li and Li, 1981). In the Wanglang Reserve, the average diameter of the nest was 32.0 cm × 26.7 cm, with a depth of 7.6 cm (n = 4) (Li et al., 1985). The differences in nest size at the various sites may be a function of the availability of local vegetation and environmental conditions. Given the concealment of nest-sites in the Gaihai-zecha forest, the, level of hinder concealment was the highest (90.83%), followed by upper concealment, left, right and center. Nests were shallow depressions lined with sticks and feathers. Of the 12 nests found, four (33.3%) were located under rock walls and covered by shrubs (Fig. 2), four (33.3%) were under trees, two (16.7%) under fallen trees and two nests were under shrubs (16.7%). Chi-squared tests showed no significant differences among nest site types (χ² = 1.333, df = 3; p = 0.721) (Wu and Liu, 2010b).

Figure  2.  Nest of a Blue-eared Pheasant located under rock walls and covered by shrubs (Photo by Yiqun WU)

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Breeding biology

The data show that the number of eggs laid by the Blue-eared Pheasant ranges between 5 to 11 per nest, with the maximum up to 15 eggs (Li et al., 1985). In Qilian County, Qinghai, clutch sizes range from 6 to 12 (Li and Li., 1981). In Pingwu County, Sichuan, the average clutch size is 7.8 (ranging from 5 to 11) (n = 6) (Li et al., 1985). In Lianhua Mountain, Gansu, the average number of eggs per nest was 9.5 (n = 4) (Sun, 2005). In the Gahai-zecha Nature Reserve, the average clutch size of this pheasant is 9.67±1.15 (n = 3). The average length of the eggs was 56.64±1.75 mm, its width 41.88±0.98 mm, egg volume 50.39±2.64 cm³ and its weight 54.97±2.87 g. Of four breeding nests, only one had successfully hatched. Man-made interference and natural enemies caused low nesting success (Figs. 3–4) (Wu and Liu, 2011).

Figure  3.  Breeding biology of Blue-eared Pheasants. (a) Nest with 9 eggs; (b) nest with 11 eggs; (c) nestlings hatched on nest; (d) nestlings in brushwood (Photo by Yiqun WU)

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Figure  4.  Blue-eared Pheasant and her nestlings in incubation period (Photo by Yiqun WU)

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The incubation period for Blue-eared Pheasants is 25–26 d. According to our observations of five nests, the hatch rate was 83.4% (Li et al., 1985). In Pingwu County, Sichuan, 24 chicks hatched from four nests, but only 16 survived; therefore the survival rate was 66.7%. Sun et al. (2005) monitored the incubation rhythm of Blue-eared Pheasants. In 2002, one female took 2–4 breaks from incubating per day, with the average break lasting 46.4±16.6 min (n = 34). Two females usually took one or two breaks per day from incubation; however, another took four breaks per day in 2003.

Feeding habits

Through analyses of stomach and ingluvies, Zhang (1959) found that the food of the Blue-eared Pheasant was composed of the seeds of Picea crassifolia and Polygonum alpinum, willow leaves, sedge and violets which together accounted for 80% of the total food intake and caterpillars and coleoptera insects for the remaining 20%. In Qilian and Menyuan, Qinghai, feeding habits of this pheasant in winter shows a preference for Potentilla anserina, fruits of Berberis vernae and Sabina tibetica, spruce seed, highland barley, broad beans and Poa annua; no grain insects and animals were found (Liao, 1984). The reason of differences in food composition in different habitats is a function of the season in which the investigation takes place; feeding insects in the breeding season can provide abundant nutrition for adult birds.

Population status and conservation

The number of Blue-eared Pheasants was once abundant, but due to deforestation and excessive hunting by local people (because of gorgeous feather, beautiful posture, and high economic value), the population has declined drastically (Lei and Lu, 2006). As well, the harm from natural enemies is one of the important reasons for this decline. According to a survey by Liao (1984), major natural enemies of the Blue-eared Pheasant are the hawk, Vulpes ferrilata, wolf, lynx and weasel (Fig. 5). Especially in the breeding and brooding periods, carnivores such as wolf and fox constantly attack the adult birds and their nestlings.

Figure  5.  Eggs of Blue-eared Pheasant damaged by natural enemies (Photo by Yiqun WU)

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Due to the lack of abundant food in winter, Blue-eared Pheasants always require larger habitats such as different types of forest or a larger range of elevations (i.e., moving from the top of a hill to the foothills and even to farmlands) to find more food sources. Therefore, some conservation measures have been recommended for this pheasant: these include strengthening the conservation of existing suitable habitats, reducing man-made interference and optimizing the landscape configuration, which would be more effective and beneficial means to promote habitat conservation of this pheasant.

Acknowledgment

This research was supported by the National Natural Science Foundation of China (30530130, 31101650).