Portal de Periódicos da CAPES

Hay Cutting and the Survival of Pheasants: A Long-Term Perspective

1989; Wiley; Volume: 53; Issue: 2 Linguagem: Inglês

10.2307/3801150

1937-2817

Richard E. Warner, Stanley L. Etter,

Genetic and phenotypic traits in livestock

We documented the fates of 1,104 ring-necked pheasant (Phasianus colchicus) nests in harvested and unharvested hayfields near Sibley, Illinois, from 1962 to 1972. A mean of 13 and 35% of nests in harvested and unharvested hay, respectively, hatched. Mortality rates of females and embryos were high when hay cutting coincided with the late stages of incubation. Dates when forage crops in the Midwest are harvested have gradually advanced since World War II, especially in the northern portions of the pheasant range where dairy and livestock production are prevalent. Over the past decade, the mean day of first cutting for alfalfa, the most widely planted hay cultivar in the Midwest, has been 3 June, about 10 days earlier than it was during the 1950's. Mortality rates for pheasant nests found after the first cutting of hay near Sibley, Illinois, were used with mean dates of the first hay cutting for Illinois to compute indices of female and nest destruction for 1951-58 and 1977-87. Indices of pheasant destruction were lower (P < 0.01) for 1977-87, which suggests that mortality of embryos and females during haying operations is, on average, easing in the Midwest due to earlier cutting. The presence of small tracts of nest cover near hayfields, if carefully managed, could enhance pheasant reproduction. J. WILDL. MANAGE. 53(2):455-461 The ring-necked pheasant range was established in North America as agricultural operations became mechanized (Leopold 1931, Schlebecker 1975). Forage crops, prime nest cover for pheasants (Hamerstrom 1936, McAtee 1945, Baskett 1947), were subjected to increasing mechanical disturbances in the 1920's and 1930's. By the 1930's it was clear that tractor-drawn cutter bars were a major threat to the survival and reproduction of female pheasants. The interplay between survival of female pheasants and eggs, and the timing of hay harvest (cutting by mowing or chopping), is delica e. Differences of a few days in harvest dates have produced variable effects on local pheasant abundance (Baskett 1947, Allen 1956, Robertson 1958). Weather, forage type, and other factors varying from farm-to-farm contribute to this i terplay. Leedy and Hicks (1945) found, for example, that nest destruction rates ranged from 75% in forage legumes and 39-64% in sweet clover and forage mixtures to 10-14% in small grains. Programs diverting farmland from production have the potential for increasing the quantity and quality of nest cover. Diverted acres buoyed numbers of pheasants in the Midwest during the 1930's, 1950's, and 1960's, when such fields persisted for several years and were free of mechanical disturbances during summer (JoI Present address: Illinois Department of Conservation, Gibson City, IL 60936. This content downloaded from 157.55.39.208 on Wed, 28 Sep 2016 05:13:41 UTC All use subject to http://about.jstor.org/terms 456 PHEASANT SURVIVAL IN HAY * Warner and Etter J. Wildl. Manage. 53(2):1989 selyn and Warnock 1964, Edwards 1984, Etter et al. 1988). These habitats also benefitted pheasants during fall and winter (Etter et al. 1988). Conversely, when set-aside programs are phased out, nesting pheasants concentrate in the remaining forages, becoming especially vulnerable to destruction during haying or grazing (Warner et al. 1987). Although the nesting of pheasants in hay has been studied in the United States, recent and long-term perspectives on hay planting and harvest practices and pheasant survival are lacking. Our objectives were to describe long-term trends in the planting of forages in the Midwest, determine post-World War II changes in the chronology of alfalfa cutting, evaluate the survival of females and embryos relative to the timing of forage harvests in Illinois, and to consider the implications of harvest dates for pheasant management and research. We thank W. L. Anderson, W. R. Edwards, G. C. Sanderson, and A. S. Hodgins of the Illinois Natural History Survey (INHS) for editorial support. G. B. Joselyn and J. E. Warnock, formerly of INHS, provided field assistance; Joselyn also reviewed an early draft of the manuscript. L. M. David, Illinois Department of Conservation (IDC) provided editorial assistance. The following forage specialists provided technical advice: D. R. Buxton, Iowa State University; D. W. Graffis, University of Illinois; and K. D. Johnson, Purdue University. This work is a contribution in part of Federal Aid Wildlife Restoration Project W-66-R, the IDC, U.S. Fish and Wildlife Service (USFWS), and INHS cooperating. The Illinois Department of Energy and Natural Resources also provided partial support. STUDY AREA AND METHODS The 9,393-ha Sibley Study Area (SSA) was located in Ford County, east-central Illinois, traditionally the prime pheasant range in Illinois (Robertson 1958, Warner 1981). The deep, dark prairie soils on the area have little relief and were farmed intensively for cash grains (Etter et al. 1988). Annual precipitation averaged 8690 cm, with approximately 67% occurring as rain from April to September. The SSA was described in detail by Joselyn et al. (1968) and Labisky (1968). We established an experimental field (EF) 10 km northeast of Sibley in 1965, to study the timing of pheasant nest establishment and hatch in unharvested forage grasses and legumes. This rectangular 9.7-ha tract was subdivided and planted with 4 mixtures of cool-season grasses and/or forage legumes, 10 replications/mixture, in a randomized block. The EF was cut in late summer, 1966-70, with a rotary mower to minimize residual cover. Fields of primarily rotation-harvested hay on the SSA were searched within 1 day of mowing or windrowing after each cutting from 1962 to 1972; 14-25 fields were searched each year, depending upon the amount of hay grown on the area. The EF was searched 2-3 times annually, 1966-70. Fields of unharvested hay were typically searched once in mid-July. Because most nests in unharvested fields could not be dated as to the time of establishment or subsequent events, these data were important primarily for comparing rates of nest success (hatch) with harvested hay. Further, success rates of pheasant nests in hay were compared to figures available for the SSA from 1957-61 (Labisky 1968). Nest search techniques are described by Joselyn et al. (1968). Nests in hayfields were categorized according to their fate including previously abandoned and/or destroyed, hatched, or active nests (embryos and sometimes F) destroyed during cutting. A frequency distribution that combined data for 1962-71 was plotted to estimate the mean rates of hatch and pheasant destruction (F and embryos) according to the week of the first hay cutting. These rates were computed based on the percent of all nests found for a given week of cutting. Pheasants were captured on the SSA by nightlighting during fall (late Oct and Nov) and winter (Jan-Feb) through 1971. After inspection for mower-related injuries (e.g., loss of a leg), females were weighed, banded and back-tagged, and released (Etter et al. 1988). The departments of agriculture in midwestern states tabulate information reported by farmers pertaining to the cropping of hay (Ill. Dep. Agric. 1987). We asked 6 state agencies to provide data reliable on a statewide basis; Illinois also provided information by region from 1981 to 1987. Most states record these data according to the percent of first and subsequent cuttings completed at 7to 10-day intervals. Using the rate of completion (% hay cut/day) between reporting intervals, we estimated the Julian date that approximated the mean (about 50% completed) day of cutting. Long-term This content downloaded from 157.55.39.208 on Wed, 28 Sep 2016 05:13:41 UTC All use subject to http://about.jstor.org/terms J. Wildl. Manage. 53(2):1989 PHEASANT SURVIVAL IN HAY * Warner and Etter 457 trends in the mean day of cutting were plotted as 3-point moving averages of the year in question and the previous 2 years. Further, for Illinois we analyzed records that described regional trends in the planting and harvesting of various hay cultivars in Illinois since 1900 (Ill. Dep. Agric. 1964, 1987). Periods selected for consideration of pheasant mortality in Illinois were 1951-58, 1977-87, and a hypothetical future series generated by subtracting 10 days from the mean cutting dates for each year from 1977 to 1987. Mean rates of female and nest destruction were assigned each year for the Illinois pheasant range by associating the mean (statewide) date of the first alfalfa cutting with destruction rates for that week as determined from the frequency distribution of nests in harvested hay on the SSA. Indices of female and nest destruction were computed for each period as the mean, standard deviation, and coefficient of variation. Although hay mowing was not observed on the SSA earlier than 21-27 May, data from the EF, and unmowed cover not in agricultural production on the SSA (Joselyn et al. 1968), indicated that rates of nest establishment nearly doubled during each week in May. Thus, rates of female and nest destruction on the SSA for 21-27 May were divided by 2 to estimate mortality rates for 14-20 May. Calculations were also made back to 30 April-6 May by dividing the female and nest mortality rates for the previous week by 2. Differences in rates of female and nest destruction for 1951-58 and 1977-87 were evaluated using 2-tailed t-tests. Zero-order regression coefficients were computed to test for changes in mean dates of hay cutting over time.