Brood Habitat Selection of Chinese ( sewerzowi) at Lianhuashan, Gansu, China Author(s): Zhao Jin-Ming, Fang Yun, Lou Ying-Qiang, and Sun Yue-Hua Source: The Wilson Journal of Ornithology, 127(2):310-318. Published By: The Wilson Ornithological Society DOI: http://dx.doi.org/10.1676/wils-127-02-310-318.1 URL: http://www.bioone.org/doi/full/10.1676/wils-127-02-310-318.1

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The Wilson Journal of Ornithology 127(2):310–318, 2015 Brood Habitat Selection of Chinese Grouse (Tetrastes sewerzowi) at Lianhuashan, Gansu, China

Zhao Jin-Ming,1,2 Fang Yun,1 Lou Ying-Qiang,1,2 and Sun Yue-Hua1,3

ABSTRACT.—We studied habitat selection in Chi- important bearing on brood success (e.g., Haulton nese Grouse (Tetrastes sewerzowi) hens with dependent 1999, Giroux et al. 2007). broods at Lianhuashan, Gansu, China in 2010–2012. We Such changes could be especially critical for the divided the dependent brood period into four stages near threatened (International Union for Conser- (weeks 1–2, 3–4, 5–8, and beyond 8 weeks post hatching) and compared used with available habitat, and found that vation of Nature 2014) Chinese Grouse (Tetrastes hens with broods chose sites with significantly less sewerzowi) because of their high chick mortality canopy cover (0.28 6 0.01 vs 0.49 6 0.02), greater during the short growing season in high-elevation willow cover (0.31 6 0.02 vs 0.14 6 0.01), and greater habitat in central China (Sun 2000; Sun et al. 2003, herb height (21.36 6 1.05 vs 14.43 6 0.59). Broods 2006). In general, Chinese Grouse’ range corre- used a variety of vegetation types at different stages of sponds to the distribution of montane coniferous chick development. They used more early successional forests between 2400–4300 meters asl, and the deciduous forests and shrubs during stages 2 and 3 (weeks 3–8, Kruskal-Wallis Test: x2 5 13.918, df 5 3, presence of willows (Salix spp.) is important P 5 0.003). Sites with more invertebrates were used in because willow leaves and buds are the main foods Stage 1 compared to available sites (54.5 6 7.2 vs for the grouse (Sun 2000, Wang et al. 2010). In 36.4 6 4.4), but not in Stage 2. Compared to sites used spring, females nest in male-established territories during stage 4, chicks in stage 2–3 used sites of earlier where there are many willow trees in mixed successional stages, greater herbaceous vegetation coniferous-deciduous forests, but little is known height, and closer proximity to forest edges, whereas about the movements and habitat needs of hens sites utilized during stage 1–3 showed visits in lower willow cover. Received 4 May 2014. Accepted 11 with broods after hatching. We hypothesized that December 2014. cover and food would be important for brood habitat selection in Chinese Grouse, and expected Key words: brood habitat, Chinese grouse, diet change, hens with broods to choose willow dominated areas early successional forests. with dense ground cover but possibly to change habitats when chicks shifted from invertebrate food to plant food. In 2010–2012, we conducted a radio Galliform chicks depend on invertebrate food telemetry study to address these questions at the in the first few weeks after hatching and gradually Lianhuashan Nature Reserve in Gansu Province, switch later to plant food, a development that may China. Our purposes were to compare sites used by be accompanied by changing habitat preferences hens with broods with those available to determine (Stewart 1956, Wallestad 1971, Drut et al. 1994). what habitat variables were most important in Broods of Ruffed Grouse (Bonasa umbellus), for determining brood habitat selection and to identify example, sometimes move to habitats with any changes in habitat preferences associated with ripening blueberries (Vaccinium spp.; Stewart the movement of hens with broods. 1956). However, many studies on brood habitat have covered only part of the brood rearing period METHODS (e.g., Steen and Unander 1985, Jones et al. 2008) Study Area.—We studied Chinese Grouse at the and may therefore have missed short-term Shahetan station in the core area of the Lianhua- changes in habitat preference that could have an shan Nature Reserve in Gansu Province of central China (34u 409 670 N, 103u 309 840 E) during 1 Key Laboratory of Ecology and Conservation 2010–2012 (Fig. 1). Of four major local vegetation Biology, Institute of Zoology, Chinese Academy of Sciences, types that can be used by Chinese Grouse, conifer Beijing 100101, People’s Republic of China. 2 University of the Chinese Academy of Sciences, Beijing forests in the center of the reserve’s core area were 100049, People’s Republic of China. dominated by spruces (Picea asperata, P. purpurea 3 Corresponding author; e-mail: [email protected] and P. wilsonii), and firs (Abies faxoniana, SHORT COMMUNICATIONS 311

FIG. 1. Location of Lianhuashan Nature Reserve in Gansu province. Main vegetation types are indicated as black (conifer forest), dark gray (conifer-deciduous forest), medium gray (deciduous forest), light gray (shrub areas), white (other habitat types including farmlands, villages, rocks, bare ground, alpine meadows, and water bodies), and white flag designates Shahetan research station.

A. fargesii) with few understory species, primarily canopy. We therefore consider the order of willows (Salix rehderiana, S. sinopurpurea, succession to be shrubs, deciduous forests, co- S. cathayana, S. taoensis, S. paraplesia, S. tangii) niferous-deciduous forests and conifer forests. and roses (Rosa omeiensis, R. tsinglingensis). Other habitat types include alpine meadow, rock Coniferous-deciduous forests, surrounding the and bare ground, farmland, villages, water bodies, conifer forests, were dominated by spruces, firs, and highway corridors. See Sun et al. (2003) for birches (Betula utilis, B. chinensis, B. albo- a more detailed description of Lianhuashan climate sinensis, B. platyphylla), and willows, with an and vegetation. understory composed of various small shrubs plus Radio Telemetry.—We attached necklace trans- birches, willows, spruces, and firs. Deciduous mitters (Model RI-2B, Holohil Systems Ltd., forests, beyond the coniferous-deciduous mixed Carp, Ontario, Canada) to 50 female Chinese forests, were dominated by birches and large Grouse during the pre-laying or incubation willows. Shrub areas, mostly at forest edges and periods of 2010–2012. Transmitters weighed openings, were dominated by willows, birches, about 9 g (less than 3% of body weight) and roses, honeysuckles (Lonicera hispida, L. cae- had an expected battery life of 12 months. We rulea), sea buckthorn (Hippophae rhamnoides), used ground nets in spring (from 28 Apr to 10 and barberry (Berberis kansuensis). Ground veg- May) and caught 15 females prior to egg-laying. etation is variable, from little vegetation to dense We then caught 35 grouse during the last week of shrubs (of a great variety of species) and also incubation (16–22 Jun) with the nets set 3–5 m grasses, arrow bamboo (Sinarundinaria nitida), from the nest and two persons walking slowly forbs, and mosses (Sun et al. 2003). Illegal logging toward the incubating hen to flush it into the net. of conifers, common before the reserve’s estab- In most cases, the hens ran off of their nests and lishment in 1983, significantly altered the forest into the nets. A few flew directly into the nets, and composition of the study area. When conifer forests one that was reluctant to flush was caught by hand were clear-cut, second-growth deciduous trees on the nest. We attached transmitters at the dominated the sites until conifers reclaimed the capture sites and released the within 10 312 THE WILSON JOURNAL OF ORNITHOLOGY N Vol. 127, No. 2, June 2015

TABLE 1. Comparison of sites used by hens with broods of Chinese Grouse and available sites using a general linear mixed model (PROC GLIMMIX) at Lianhuashan, Gansu, China, 2010–2012. Used sites and paired available sites as a random effect (n 5 107).

Used Sites Available Sites

Variables Mean SE Range Mean SE Range FP Canopy Cover (%) 0.28 0.01 0–0.7 0.49 0.02 0–0.8 16.86 ,0.001 Tree Number 12.81 0.75 0–39 19.64 0.95 0–52 0.70 0.4024 Tree Species 1.74 0.08 0–3 1.71 0.07 0–3 2.58 0.1096 dbh (cm) 18.47 0.77 0–36 20.73 0.64 0–41 0.39 0.5335 Tree Height (m) 15.90 0.71 0–28 19.14 0.64 0–38 0.20 0.6549 Shrub Height (m) 2.94 0.09 0.6–5.4 2.60 0.09 0.5–5 0.35 0.5549 Shrub Cover (%) 0.43 0.01 0.2–0.8 0.32 0.01 0.1–0.8 0.49 0.4867 Willow Cover (%) 0.31 0.02 0–0.7 0.14 0.01 0–0.7 10.15 0.0017 Willow Height (m) 3.02 0.13 0–7 2.23 0.19 0–9 0.59 0.4451 Horizontal Cover1 (%) 0.54 0.02 0.2–1 0.41 0.02 0.2–0.8 0.04 0.8484 Horizontal Cover2 (%) 0.58 0.02 01.–0.9 0.44 0.02 0–0.8 0.31 0.5787 Horizontal Cover3 (%) 0.47 0.02 0–0.8 0.37 0.01 0.1–0.9 0.01 0.9114 Herb Cover (%) 0.63 0.02 0.2–0.9 0.54 0.02 0.1–0.9 0.22 0.6405 Herb Height (cm) 21.36 1.05 6–70 14.43 0.59 2.5–30 4.01 0.0465 Dead Wood (m3) 0.07 0.01 0–0.6 0.07 0.02 0–1.2 0.88 0.3501 Bamboo number 0.33 0.06 0–3 0.38 0.06 0–4 3.32 0.0700 Distance to Edge (m) 186.2 17.78 0–800 206.64 16.47 15–800 0.32 0.5697 Distance to Water (m) 53.94 5.75 0–300 63.85 6.10 4–400 1.00 0.3176 Slope Aspect (u) 215.9 11.81 10–355 204.67 12.71 0–350 0.33 0.5649 Slope Gradient (u) 15.91 1.37 0–85 19.38 1.17 0–60 0.23 0.6324

mins. All hens returned their nests in ,20 mins defined used points as locations of hens with and no nests were deserted because of capture broods established by visual contact, and available procedure. Nests were monitored until hatching, points as sites 50 m away from the used sites predation, or desertion. We considered a nest taken on a random bearing. At used and available successful if at least one egg hatched. sites, we measured 20 variables including vege- After grouse hatched or nests were depredated, tation and terrain factors in a 20 x 20 m plot. We we tracked hens until brood break-up in early fall recorded slope aspect (from 0–359u) and slope (range: 24 Aug to 12 Oct), locating them at least gradient using a compass. Canopy cover, shrub once a week using a 2-element Yagi antenna cover, willow cover, and herb cover were (Biotrack Ltd., Dorset, UK) and a portable receiver measured using the line intercept method (Can- (Telonics Inc., Mesa, AZ, USA). Of 50 radioed field 1941) along two 20-m lines in two main hens, nests of 34 were successful. No hens re- directions perpendicularly crossing the center of nested after nest predation during their incubation the site. The height of trees .5 m, shrubs, willows period but four had transmitter malfunctions, two and herbs were measured at 5-m intervals and were depredated, and four lost their broods before then averaged. Diameter at breast height (dbh) of we assessed their habitat use. We therefore trees was measured using a tape measure (Dil- collected data from the remaining 24 hens with worth and Bell 1980). Average maximum height broods supplemented by observations of a few of herbs was recorded and herb coverage was other untracked hens with broods encountered estimated by 20 x 50 cm PVC frame (Daubenmire while tracking radioed hens (hatching dates for 1959). Horizontal cover was measured using these hens were assumed to be equal to the mean a cover board (2.5-m height, 0.5-m width), which hatching data of hens in the corresponding year was divided into three parts of different colors; and we excluded data of uncertain chick ages). 0–1 m was defined as horizontal cover 1, 1–2 m as Habitat Sampling.—We judged if hens had horizontal cover 2, and .2 m as horizontal broods by seeing the chicks, hearing hen alert cover 3. The cover board was placed vertically calls, or seeing distraction displays by hens. We in the center of used and available sites, with the SHORT COMMUNICATIONS 313

no bamboo stems/m2,1as,10 stems/m2,2as 10–30 stems/m2,3as.30 stems/m2. We classi- fied bamboo number to one of the four categories in the field according to values averaged from four 2 x 2 m samples centered 2.5 m from the sample center along the two intercept lines. Dead wood volume was calculated in m3 using dead stems with diameter .10 cm within 2 m of the two intercept lines. Slope aspect and slope gradient was measured in degree (u). Vegetation type was defined as forest (vs shrub land) when canopy cover exceeded 10%. Forest type was further defined as conifer forest when conifer trees made up . 75% of canopy cover, as conifer- deciduous forest when canopy cover was ,25– FIG. 2. Percent of four different vegetation types used 75%, and as deciduous forest when canopy cover by hens with broods of Chinese Grouse in four different was ,25% coniferous. brooding stages at Lianhuashan, Gansu, China, 2010–2012. To sample invertebrates, we made 40 sweeps with a 40-cm diameter scoop net on a 1.2-m observer 5 m away to estimate the coverage of pole in dry (dewless) conditions along our two each part indicated by a score (%). Every score intersecting lines at all used and available sites was estimated four times from four different during the first 4 weeks post hatching. We killed directions and the mean was used for analysis collected invertebrates immediately using (Nudds 1977, Yang et al. 2011). Distance to edge methenyl chloride and identified them to order was defined as the distance from sites to a different with the aid of an 83 microscope (Burke et al. habitat type. Bamboo number was defined as: 0 as 2008).

TABLE 2. Variables compared between four brood-rearing stages at sites used by hens with broods of Chinese Grouse at Lianhuashan, Gansu, China, 2010–2012. Different capital letters indicate significant differences between brood-rearing stages; 6 1 SE in parentheses.

1–2 weeks 3–4 weeks 5–8 weeks 8 weeks-

Periods n 5 27 n 5 25 n 5 31 n 5 24 Canopy cover (%) 0.37 (0.02)A 0.29 (0.04)A 0.19 (0.02)B 0.30 (0.01)A Tree number 16.6 (1.4)A 12.5 (1.9)AB 10.3 (1.4)B 12.1 (0.9)AB Tree species 1.9 (0.1)AB 1.4 (0.2)B 1.5 (0.2)B 2.2 (0.1)A dbh (cm) 21.6 (1.0)A 16.0 (1.7)B 14.8 (1.7)B 22.2 (0.9)A Tree Height (m) 19.4 (1.0)A 14.0 (1.6)B 13.3 (1.6)B 17.3 (1.1)AB Shrub Height (m) 2.87 (0.15) 2.69 (0.20) 2.98 (0.18) 3.25 (0.19) Shrub Cover (%) 0.38 (0.02)B 0.42 (0.03)AB 0.45 (0.02)AB 0.49 (0.02)A Willow Cover (%) 0.26 (0.03)B 0.26 (0.03)B 0.30 (0.02)B 0.44 (0.03)A Willow Height (m) 2.94 (0.23)B 2.56 (0.33)B 2.85 (0.23)B 3.80 (0.21)A Horizontal Cover1 (%) 0.47 (0.03)B 0.58 (0.07)AB 0.53 (0.02)AB 0.58 (0.03)A Horizontal Cover2 (%) 0.53 (0.04) 0.56 (0.04) 0.58 (0.03) 0.65 (0.03) Horizontal Cover3 (%) 0.41 (0.03)B 0.46 (0.04)AB 0.47 (0.03)AB 0.53 (0.02)A Herb cover (%) 0.64 (0.03) 0.62 (0.03) 0.67 (0.03) 0.57 (0.03) Herb Height (cm) 18.4 (0.9)BC 20.4 (1.7)B 28.8 (2.5)A 16.1 (1.8)C Dead wood (m3) 0.10 (0.03) 0.05 (0.02) 0.04 (0.02) 0.07 (0.03) Bamboo number 0.37 (0.13) 0.28 (0.12) 0.26 (0.11) 0.42 (0.12) Distance to Edge (m) 291.5 (41.5)A 106.5 (28.3)B 87.1 (13.5)B 279.2 (37.0)A Distance to Water (m) 31.0 (5.9)B 65.2 (14.7)AB 52.3 (10.0)AB 70.2 (13.7)A Slope Aspect (u) 290.9 (18.8) 173.6 (25.8) 185.6 (18.5) 214.8 (25.4) Slope Gradient (u) 11.3 (3.3)B 16.5 (2.7)AB 17.6 (2.7)AB 18.3 (1.8)A 314 THE WILSON JOURNAL OF ORNITHOLOGY N Vol. 127, No. 2, June 2015

TABLE 3. Results of model selection using unconditional logistic regression for brood habitat use in four brood rearing stages of Chinese Grouse at Lianhuahsna, Gansu, China, 2010–2012. A total of 107 observations were used for the analyses.

a b c d e f Model k -2LL AICC DAICC wi TH+WC+HH+DE 15 200.218 235.493 0.000 0.840 WC+HH+DE 12 211.902 239.221 3.728 0.130 TH+SC+WC+HH+DE 18 198.863 242.636 7.143 0.024 TH+SC+WC+HH+DE+SG 21 192.62 245.491 9.998 0.006 TH+SC+WC+HH+DE+DW+SG 24 189.195 251.829 16.336 0.000 Intercept 3 295.613 301.846 18.001 0.000 TH 6 281.772 294.612 21.254 0.000 WC+DE 9 238.292 258.148 22.655 0.000 TH+SC+WC+WH+HH+DE+DW+SG 27 187.323 260.462 24.970 0.000 CC+TH+SC+WC+WH+HH+DE+DW+SG 30 177.498 261.972 26.479 0.000 WC 6 273.229 286.069 27.921 0.000 DE 6 260.518 273.358 30.722 0.000 CC+DBH+TH+SC+WC+WH+HH+DE+DW+SG 33 173.532 270.272 34.779 0.000 CC+TS+DBH+TH+SC+WC+WH+HH+DE+DW+SG 36 167.468 277.525 42.032 0.000 HH 6 271.005 283.845 44.624 0.000

a CC canopy cover, TS tree species, TH tree height, DBH diameter at breast height, SC shrub cover, WC willow cover, WH willow height, HH herb height, DE distance to edge, DW distance to water, SG slope aspect b k the number of parameters. c -2LL the log-likelihood. d AICC Akaike Information Criterion adjusted for small samples. e DAICC the scale of AICC relative to the top model. f wi model weight.

Statistical Analyses.—We compared used and hatching) hens and their broods remained within available sites employing PROC GLIMMIX with 40–800 m (210.7 6 22.4 m, mean 6 SE, n 5 53) paired used sites and available sites as a random of the nest site. In Stage 2 (weeks 3 and 4), they effect in SAS 9.1 (SAS Institute 2003, Cary, NC, left the vicinity of the nest site and wandered up to USA). We divided the brood period into four 100–5010 m (1488.3 6 194.7 m, n 5 39) away. In stages according to the movement patterns of hens Stage 3 (weeks 5–8), they remained far (140–5890 with broods. In Stage 1 (weeks 1 and 2 post m) from nest sites (2144.3 6 169.9 m, n 5 61).

TABLE 4. Parameter estimate and odds ratio of the four variables significantly different between brood rearing stages of Chinese Grouse from the best model determined by Akaike Information Criterion adjusted for small samples (AICC) and model weight (wi) at Lianhuashan, Gansu, China, 2010–2012. Brood rearing stage 4 (8 weeks post-hatching) was used as the reference group.

Variables Weeks df Estimate SE x2 P Odds 95%CI Intercept 1–2 1 2.013 2.171 0.86 0.354 Intercept 3–4 1 5.152 2.088 6.088 0.014 Intercept 5–8 1 3.881 2.102 3.41 0.065 Tree Height 1–2 1 20.017 0.072 0.056 0.813 0.983 0.854 1.132 Tree Height 3–4 1 20.155 0.07 4.921 0.027 0.857 0.747 0.982 Tree Height 5–8 1 20.151 0.071 4.549 0.033 0.860 0.749 0.988 Willow Cover 1–2 1 210.776 2.849 14.311 ,0.001 ,0.001 ,0.001 0.006 Willow Cover 3–4 1 211.659 3.091 14.226 ,0.001 ,0.001 ,0.001 0.004 Willow Cover 5–8 1 211.762 3.176 13.714 ,0.001 ,0.001 ,0.001 0.004 Herb Height 1–2 1 0.112 0.056 4.078 0.043 1.119 1.003 1.247 Herb Height 3–4 1 0.154 0.059 6.825 0.009 1.167 1.039 1.310 Herb Height 5–8 1 0.223 0.06 13.78 ,0.001 1.250 1.111 1.405 Distance to Edge 1–2 1 ,0.001 0.002 0.196 0.658 1.001 0.997 1.005 Distance to Edge 3–4 1 20.007 0.003 6.717 0.01 0.993 0.988 0.998 Distance to Edge 5–8 1 20.009 0.003 8.35 0.004 0.991 0.986 0.997 SHORT COMMUNICATIONS 315

FIG. 3. Differences between four variables in different brood rearing stages determined by unconditional logistic regression at Lianhuashan, Gansu, China, 2010–2012. Bars 5 6 1 SE.

Finally, in Stage 4 (weeks 9–11 post hatching), they distributed or PROC NPAR1WAY when data moved back to the Stage 1 areas close (20–1300 m) were not distributed normally and could not be to their nests (245.6 6 70.5 m, n 5 19) transformed to normality. Second, variables with and remained there until brood break-up at ,10– significant differences were compared mutually 11 weeks post-hatching. using PROC CORR. Whenever a correlation We compared used habitat variables between between two variables exceeded 0.6, only one the four stages using the unconditional logistic variable was retained in the next analysis. Third, method (PROC LOGISTIC) with the aid of we set up a model including all significant Akaike Information Criterion (AIC; Burnham variables, and used unconditional logistic re- and Anderson 2002). First, we compared used gression with an alpha level at 0.05 for variable sites between four brood rearing stages using inclusion or removal (Hartzel et al. 2001, Sergio t-tests (PROC TTEST) when data were normally et al. 2003). ‘‘Brood-rearing stages’’ was the

TABLE 5. Comparison of invertebrate numbers between used sites of hens with broods of Chinese Grouse and available sites in stage 1 and stage 2 of the brood-rearing period at Lianhuashan, Gansu, China, 2010–2012; 6 1SE in parentheses.

1–2 Weeks (n 5 24) 3–4 Weeks (n 5 15)

Categories Used Available ZP Used Available ZP Arachnoidea 6.7(1.6) 3.9(0.8) 1.548 0.122 4.3(0.9) 3.3(0.8) 0.883 0.377 Diptera 11.8(1.9) 7.5(1.4) 1.955 0.051 14.2(2.1) 13.3(2.3) 0.479 0.632 Hymenoptera 6.7(1.3) 4.3(0.8) 1.162 0.245 4.7(1.3) 5.4(1.6) 0.378 0.706 Coleoptera 3.3(0.6) 2.2(0.6) 2.138 0.033 0.7(0.3) 1.1(0.4) 0.901 0.368 Hemiptera 24.2(4.4) 18.0(3.0) 0.918 0.359 10.6(2.3) 11.5(2.5) 0.000 1.000 Lepidoptera 1.7(0.4) 1.0(0.3) 1.399 0.162 1.5(0.5) 0.8(0.2) 0.895 0.371 Total 54.5(7.2) 36.4(4.4) 2.053 0.040 35.7(4.0) 35.5(5.0) 0.125 0.901 316 THE WILSON JOURNAL OF ORNITHOLOGY N Vol. 127, No. 2, June 2015 dependent variable and had four categories. Any Hens with broods chose sites with smaller trees in of the categories could be chosen to be the stage 3 than in stage 4 (13.3 6 1.6 m vs 17.3 6 1.1 reference; only the values and interpretation of the m; OR 5 0.87, P 5 0.011), sites with less willow coefficients will change, so we chose brood cover in stages 1–3 than in stage 4 (0.26 6 0.03, rearing stage 4 as reference (Hosmer and 0.26 6 0.03, 0.30 6 0.02 vs 0.44 6 0.03; OR , Lemeshow 2000). All of our model development 0.001; P 5 0.000, P 5 0.000, P 5 0.001), and sites and selection were based on Akaike Information with greater herb height in stages 2–3 than in stage Criterion adjusted for small samples (AICC; 4 (20.4 6 1.7 cm, 28.8 6 2.5 cm vs 16.1 6 1.8 cm; Johnson and Omland 2004). The most parsimoni- OR 5 1.119, OR 5 1.167 and OR 5 0.250; P 5 ous model with the smallest value was considered 0.045, P 5 0.034 and P 5 0.000) and that were the best model. The model weight (wi) was used to closer to forest edges in stages 2 and 3 than in stage indicate the probability of the best model (Hosmer 4 (291.5 6 41.5 m, 106.5 6 28.3m,87.16 13.5 and Lemeshow 2000). Odds ratio (OR; Zhang and m, 279.2 6 37.0 m; OR 5 0.993, OR 5 0.991; P 5 Yu 1998, Bland and Altman 2000) was used to 0.001, P 5 0.000) (Table 4; Fig. 3). compare whether the probability of a certain event Sites with more invertebrates were selected by was the same for two groups. hens with broods in stage 1 (54.5 6 7.2 vs 36.4 6 We compared invertebrate numbers between 4.4; P 5 0.040) but not in stage 2 (35.7 6 4.0 vs used sites and available sites in brood-rearing 35.5 6 5.0; P 5 0.901; Table 5). stage 1 and stage 2, hypothesizing that brood diet would shift from invertebrates towards plant food DISCUSSION corresponding to their habitat shift 2 weeks post Compared to available sites, those used by hatching. All results are presented as mean 6 SE. Chinese Grouse hens with broods were character- ized by less canopy cover, greater willow cover, RESULTS and greater herb height throughout the entire Compared with available sites, those chosen by brood-rearing period. Less canopy cover allows hens with broods had less canopy cover (0.28 6 more sunlight to reach lower vegetation layers, 0.01 vs 0.49 6 0.02), greater willow cover (0.31 supporting greater shrub and herbaceous growth, 6 0.02 vs 0.14 6 0.01), and greater herb height greater invertebrate biomass, and consequently (21.36 6 1.05 cm vs 14.43 6 0.59 cm; Table 1). better food resources and concealment possibili- A variety of habitat types were used during the ties for grouse chicks. Similar results were also brood-rearing period (Fig. 2). Especially in stages found in Ruffed Grouse (Tirpak et al. 2008), 2–3 (weeks 3–8), hens with broods chose earlier (Tetrao urogallus), and successional stages (Kruskal-Wallis Test: x2 5 Black Grouse (Lyrurus tetrix; Wegge and Kast- 13.918, df 5 3, P 5 0.003), as indicated by dalen 2008). The importance of willow buds and smaller trees, less canopy cover, and greater herb leaves as food for adult Chinese Grouse has height (Table 2; Fig. 3). We investigated 20 already been documented (Sun et al. 2003), and habitat variables to evaluate differences among the structure of willow thickets almost certainly the four brood-rearing stages. A general linear helps to conceal chicks from potential predators. model showed that canopy cover, tree number, Similarly, greater sagebrush (Artemisia triden- tree species, dbh, tree height, shrub cover, willow tata) cover has been shown to be the most cover, willow height, herb height, distance to important variable in brood habitat selection in edge, distance to water and slope aspect were the Greater Sage-Grouse (Centrocercus uropha- different between the four brood rearing stages. sianus; Aldridge and Brigham 2002). The correlation coefficient r of canopy cover and We found that hens with broods chose a variety tree number was 0.762, so tree number was of habitat types during the brood-rearing period removed from the logistic regression analysis. Of and earlier successional stages were selected in the 15 models analyzed and compared by AICC stages 2–3 (weeks 3–8; Fig. 2). Preference for (Table 3), the most supported one (wi 5 0.840) early stages of forest succession are commonly included tree height, willow cover, herb height, found in forest grouse species, including Ruffed and distance to edge as explanatory variables. The Grouse (Scott et al. 1998, Giroux et al. 2007), most important used-site differences among the Black Grouse (Signorell et al. 2010), Western four brood-rearing stages were tree height, willow Capercaillie (Børset and Krafft 1973), and Hazel cover, herb height, and distance to edge (Table 3). Grouse (Tetrastes bonasia; Sun and Fang 1997). SHORT COMMUNICATIONS 317

The same is also true of some other galliform matrix, consisting of a mosaic of early succes- species such as Gray (Perdix perdix; sional forests, including extensive willow cover Panek 1997) and Wild Turkey (Meleagris gallo- (0.30 6 0.03, height 2.84 6 0.23m), numerous pavo; Campo et al. 1989). Early successional forest edges or openings, and greater herb height forests and shrubs may supply Chinese Grouse (28.8 6 2.5cm), to provide suitable brood-rearing chicks with more succulent forb food species such habitats in the vicinity of nesting habitat. For the as the strawberry (Fragaria orientalis). relatively small Lianhuashan reserve, we recom- Selection for greater herb height and greater mended enlarging its protected areas to include proximity to forest edges in stages 2–3 (weeks young forests and forest edges. 3–8 post hatching) have also been found in other forest grouse species (Tirpak et al. 2008, Signorell ACKNOWLEDGMENTS et al. 2010). Forest-edge sites are known to have This research was supported financially by the National greater variety of herbaceous species and insects, Natural Foundation of China (Project 31372210). We thank both of which are eaten by grouse chicks (Bump staff of the Lianhuashan Nature Reserve for their invaluable et al. 1947, Wallestad 1971, Thompson et al. assistance, and Li YaHui, Cheng WenDa, Jiang YingXin, 2006). The greater herb height on used sites in Li JinLin, Shi Mei and Hong Yang for their help with field stages 2 and 3 compared to stage 1 (20.4 6 1.7 work. We are also grateful to Yang Chen and Lyu Nan for comments on an earlier draft, and to Huw Lloyd and Dan cm, 28.8 6 2.5 cm vs 18.4 6 0.9 cm) may also Strickland for their comments and help with English. be advantageous insofar as rapidly growing chicks need increasingly taller cover for effective LITERATURE CITED concealment. Galliform chicks need protein-rich invertebrate ALDRIDGE,C.L.AND R. M. BRIGHAM. 2002. 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