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1 March 1996 Natality of ruffed grouse Bonasa umbellus in central Wisconsin, USA
Robert J. Small, James C. Holzwart , Donald H. Rusch
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Radio-marked female ruffed grouse Bonasa umbellus were monitored in central Wisconsin, USA, during 1983–1988 to estimate nesting rates (the percentage of hens that initiate a clutch), clutch size, nest success, and the prevalence and success of renests. All 23 radio-marked females initiated a clutch, 22 completed a first clutch; the remaining hen was killed by a predator during laying. Mean clutch size of first nests was 11.0 ± 0.5 eggs (range = 7–13). Five of nine (56%) hens attempted to renest with a mean clutch size of 7.4 ± 1.3 eggs (range = 6–9). Mean nest success was 46%; 43% for yearlings and 60% for adults. First nests produced the large majority of eggs that hatched (86.1%) compared to renests (13.9%). Productivity was estimated at 5.8 chicks hatched for each hen alive on 20 April, the mean date of the first egg laid.

Natality among tetraonids varies greatly, depending on food, predation pressure, nesting cover, age, social interactions, etc. (Keppie 1981, Bergerud 1988, Martin et al. 1989, Jonsson et al. 1991). Little is known about the natality of ruffed grouse, even though it is a well studied species. Although clutch size and nest success have been estimated for ruffed grouse (see Bergerud 1988), there is a paucity of information on two critical components of natality: 1) the percentage of hens that initiate a clutch, and 2) the prevalence and success of renests. Thus, we present additional information on these components of the bird's natality.

Bump et al. (1947) speculated that up to 25% of ruffed grouse hens did not breed in some years; yet, this was an indirect estimate prior to the use of radio-telemetry. Brander (1967) radio-marked four hens and located nests for the three yearlings but not for the adult. Maxson (1978), using telemetry, recorded 100% of hens (N = 15) nested in contiguous mixed-hardwood forests during a cyclic population high in Minnesota, USA. However, some hens were captured on the nest during this study, thereby precluding an accurate estimate of the percentage of hens that attempted to nest. Maxson (1977) also provided the first indirect evidence of a renesting attempt by ruffed grouse.

Our objective was simply to increase the limited amount of information on ruffed grouse natality by studying a population in the fragmented forests of central Wisconsin, USA. We estimated nesting rates (the percentage of females initiating a clutch), clutch size, nest success, and the prevalence and success of renesting by monitoring radio-marked yearling and adult female grouse.

Study area and methods

The study was conducted during 1983–88 in Marquette and Waushara counties in central Wisconsin (44°01′N, 89°23'W). The study area was a mosaic of forests (36%), cropland and pasture (48%), commercial forest of Red pine Pinus resinosa (8%), and marsh lands (8%) (Small & Rusch 1989).

We trapped hens from July through November, and in April and May using lily-pad traps (Dorney & Mattison 1956). We also recaptured some hens at the nest to replace transmitters. We estimated age by molt progression (Hale et al. 1954) and calamus diameter ratios (Rodgers 1979). We fitted hens weighing >350g with a 16–21 g radio-transmitter attached to a poncho (Amstrup 1980), and one anodised aluminum leg band; hens ≤350g were not fitted with a radio-transmitter. Hens less than 12 months of age were classified as yearlings, all others as adults. To estimate the date of first egg and hatch date, we assumed laying rates of 1.5 days per egg and an incubation period of 23 days (Bump et al. 1947:288).

Table 1.

Ruffed grouse nest success, clutch size, and hatch success in Marquette and Waushara counties, Wisconsin, USA, 1983–1988“.

Once their nest was found each female was located by triangulation every other day, followed by a visit to the nest on the predicted hatch date to estimate the number of eggs that successfully hatched. If the estimated location of the hen diverged from the nest, we examined the nest to estimate the time and cause of nest failure. If a first clutch was destroyed we continued to monitor the hen to estimate renesting occurrence and success. Due to the relatively small number of first nest attempts (N = 23) observed during the study, we did not perform statistical analyses to examine potential age-specific differences in nesting parameters.


A total of 23 radio-marked hens survived until 20 April, the mean date of the first egg laid. Only one hen was captured in spring, on 27 March, approximately 25 days before she laid her first egg. Twenty-two of the 23 radiomarked hens completed a first clutch during 1983–88; the remaining hen was killed by a predator after laying four eggs. Predators destroyed nine complete first clutches and killed one additional hen. Two completed clutches were accidentally destroyed during recapture attempts and were excluded from the remaining analyses for first nest attempts; one of the hens whose nest was destroyed renested. A clutch of 13 eggs did not hatch because of infertility or early embryonic death; the hen incubated these inviable eggs for 52 days. Based on these results, we calculated first nest success at 48%, with a mean first clutch size of 11.0 ± 0.5 eggs (Table 1).

Fifty-six percent of hens which survived after their first nests were destroyed attempted to renest, with a renest success of 40% and a mean clutch size of 7.4 ± 1.3 eggs (see Table 1). Renesting hens incubated their first clutch for an average of 9.4 days (range = 5–18), and began laying their second clutch 4.8 days after nest destruction (12–27 May). The difference in first clutch size between hens that renested and hens that did not was minimal (10.6 vs. 11.6 eggs). Precise estimates of first nest initiation and destruction were recorded for only five hens; the mean time invested (days of egg laying and incubation) in first nests was similar for the three hens which renested compared to the two that did not (22.0 vs. 21.5 days).

Combined nest success was 46%; 43% for yearlings and 60% for adults. Combined hatch success was 44.9% for nests in which at least one egg hatched, and did not differ significantly between yearlings and adults (z = 1.25, P = 0.21, see Table 1). The mean number of eggs hatched was 9.9 and 8.0 for successful first nests and renests, respectively, with overall productivity estimated at 5.8 (115/20) chicks hatched for each hen alive on 20 April. Of 115 eggs hatched from 256 total laid, the large majority were from first nest attempts compared to renests (86.1% vs. 13.9%). We did not detect any possible effects of radio-transmitters on breeding hens, yet we did not monitor unmarked hens for a proper comparison.


The 100% nesting rate of ruffed grouse observed in our study supports previous results of Brander (1967) and Maxson (1978). Although Bump et al. (1947: 359) speculated that nesting rates could be as low as 75% for ruffed grouse, their inference may have been biased by indirect estimates. The radio-telemetry studies of nesting hens suggest, therefore, that high nesting rates are common for ruffed grouse. These comparable results were recorded at both high and low densities (this study; see Small et al. 1991), and in both fragmented and contiguous forests, implying that nesting may neither be limited by social exclusion (Hannon et al. 1982) nor by nesting habitat. Finally, high nesting rates by ruffed grouse would follow Bergerud's (1988:580) conclusion of forest grouse in general: “… nearly all adult females breed and nest and that most yearlings attempt to do so”. However, Hannon & Zwickel (1987) reported that a small percentage of females may not nest in some blue grouse Dendragapus obscurus populations.

The 46% nest success rate for ruffed grouse observed in our study is lower than the 61% mean rate summarised from 13 studies by Bergerud (1988: 593). Our lower nest success rate could be a result of the high proportion of yearlings in the sample, as our trapping effort was directed primarily towards yearlings. Adults (N = 5) comprised only 22% of our marked population, a percentage lower than expected from age-specific survival estimates from the same study (Small et al. 1991), and from age ratios reported from other ruffed grouse populations (Rusch & Keith 1971). As yearling female ruffed grouse generally exhibit a lower nest success than adults (61% vs. 71%, Bergerud 1988: 600; 43% vs. 60% our study), the bias towards yearlings in our sample would yield a lower nest success estimate. Finally, the large majority (91 %) of nest failures in our study was due to destruction by predators, typical for tetraonids (Bergerud 1988: 593, Storch & Willebrand 1991). Perhaps, the extensive fragmentation within our study area may have increased nest predation, consistent with results from other studies (e.g. Andren et al. 1985, Wilcove 1985) which indicate that forest fragmentation increases nest predation.

The proportion of hens that renested after their first nest was destroyed in our study was 56% and this is a substantially higher proportion than the 12–22% reported previously for ruffed grouse (Bump et al. 1947: 364, Maxson 1977). In addition, the amount of parental investment in the first clutch did not appear to determine whether a hen would initiate a second clutch. The high percentage of ruffed grouse hens renesting in our study is more typical of steppe grouse according to Bergerud (1988: 597), as the percentage of forest grouse hens that usually renest is relatively low, e.g., blue grouse 25% (Sopuck & Zwickel 1983), and spruce grouse Dendragapus canadensis 10% (Ellison 1974). However, Willebrand (1992) reported a renesting frequency of 53% among radio-marked black grouse Tetrao tetrix. Thus, we contend that such generalisations be considered tenuous until larger samples of nesting females of both forest and steppe grouse are monitored by radio-telemetry.


we thank the personnel of the Wautoma field station of the Wisconsin Department of Natural Resources (WDNR) for assistance throughout the fieldwork, and the research assistants that aided in data collection. We thank the private landowners of Marquette and Waushara counties, without whose cooperation the project would not have been possible. L. Sileo, S.A. Temple, S.R. Craven, C.G. Lorimer, and J.E. Botero reviewed the manuscript. Financial support was provided by the Bureau of Wildlife Management and Research of WDNR. The Cooperative Wildlife Research Unit is supported by the University of Wisconsin-Madison, WDNR, United States Fish and Wildlife Service, and the Wildlife Management Institute.



Amstrup, S.C. 1980: A radio-collar for game birds. - Journal of Wildlife Management 44: 215–217. Google Scholar


Andrén, H., Angelstam, P., Lindstrom, E. & Widén, P. 1985: Differences in predation pressure in relation to habitat fragmentation: an experiment. - Oikos 45: 273–277. Google Scholar


Bergerud, A.T. 1988: Population ecology of North American grouse. - In: Bergerud, A.T. & Gratson, M.W. (eds.); Adaptive strategies and population ecology of northern grouse. Vol. 2. University of Minnesota Press, Minneapolis, pp. 578–684. Google Scholar


Brander, R.B. 1967: Movements of female ruffed grouse during the mating season. - Wilson Bulletin 79: 28–36. Google Scholar


Bump, G., Darrow, R.W., Edminster, F.C. & Crissey, W.F. 1947: The ruffed grouse: life history, propagation, management. - New York State Conservation Department, 951 pp. Google Scholar


Dorney, R.S. & Mattison, H.M. 1956: Trapping techniques for ruffed grouse. - Journal of Wildlife Management 20: 47–50. Google Scholar


Ellison, L.N. 1974: Population characteristics of Alaskan spruce grouse. - Journal of Wildlife Management 38: 383–395. Google Scholar


Hale, J.B., Wendt, R.F. & Halazon, G.C. 1954: Sex and age criteria for Wisconsin ruffed grouse. - Wisconsin Conservation Department Technical Wildlife Bulletin Number 9, 24 pp. Google Scholar


Hannon, S.J., Sopuck, L.G. & Zwickel, F.C. 1982: Spring movements of female blue grouse: evidence for socially induced delayed breeding in yearlings. - Auk 99: 687–694. Google Scholar


Hannon, S.J. & Zwickel, F.C. 1987: Spacing behaviour and population regulation in female blue grouse. - Auk 104: 344–347. Google Scholar


Jonsson, K.I., Angelstam, P.K. & Swenson, J.E. 1991: Patterns of life-history and habitat in Palearctic and Nearctic forest grouse. - Ornis Scandinavica 22: 275–281. Google Scholar


Keppie, D.M. 1981: A difference in production and associated events in two races of spruce grouse. - Canadian Journal of Zoology 60: 2116–2123. Google Scholar


Martin, K., Hannon, S.J. & Rockwell, R.F. 1989: Clutch size variation and patterns of attrition in fecundity of willow ptarmigan. - Ecology 70: 1788–1799. Google Scholar


Maxson, S.J. 1977: Activity patterns of female ruffed grouse during the breeding season. - Wilson Bulletin 89: 439–455. Google Scholar


Maxson, S.J. 1978: Spring home range and habitat use by female ruffed grouse. - Journal of Wildlife Management 42: 61–71. Google Scholar


Rodgers, R.D. 1979: Ratios of primary calamus diameters for determining age of ruffed grouse. - Wildlife Society Bulletin 7: 125–127. Google Scholar


Rusch, D.H. & Keith, L.B. 1971: Seasonal and annual trends in numbers of Alberta ruffed grouse. - Journal of Wildlife Management 35: 803–822. Google Scholar


Small, R.J. & Rusch, D.H. 1989: The natal dispersal of ruffed grouse. - Auk 106: 72–79. Google Scholar


Small, R.J., Holzwart, J.C. & Rusch, D.H. 1991: Predation and hunting mortality of ruffed grouse in central Wisconsin. - Journal of Wildlife Management 55: 512–520. Google Scholar


Sopuck, L.G. & Zwickel, F.C. 1983: Renesting in adult and yearling blue grouse. - Canadian Journal of Zoology 61: 289–291. Google Scholar


Storch, I. & Willebrand, T. 1991: Workshop summary: Management implications of nest and brood predation in grouse. - Ornis Scandinavica 22: 271–272. Google Scholar


Wilcove, D.S. 1985: Nest predation in forest tracts and the decline of migratory songbirds. - Ecology 66: 1212–1214. Google Scholar


Willebrand, T. 1992: Breeding and age in female black grouse Tetrao tetrix. - Ornis Scandinavica 23: 234–238. Google Scholar
Robert J. Small, James C. Holzwart , and Donald H. Rusch "Natality of ruffed grouse Bonasa umbellus in central Wisconsin, USA," Wildlife Biology 2(1), 49-52, (1 March 1996).
Received: 17 November 1995; Accepted: 27 February 1996; Published: 1 March 1996
Bonasa umbellus
clutch size
nest success
ruffed grouse
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