https://cpw.cvlcollections.org/files/original/bd83776038bb401409ea09ebacc444ce.pdf 0672492a58351ea7fd61f58ad622e88d PDF Text Text The research in this publication was partially or fully funded by Colorado Parks and Wildlife. Dan Prenzlow, Director, Colorado Parks and Wildlife • Parks and Wildlife Commission: Marvin McDaniel, Chair • Carrie Besnette Hauser, Vice-Chair Marie Haskett, Secretary • Taishya Adams • Betsy Blecha • Charles Garcia • Dallas May • Duke Phillips, IV • Luke B. Schafer • James Jay Tutchton • Eden Vardy �RESPONSE OF WATERBIRDS TO EXPERIMENTAL DISTURBANCES JANET L. GEORGE 1 , Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523 CLAIT E. BRAUN, Colorado Division of Wildlife, Wildlife Research Center, 317 West Prospect Road, Fort Collins, CO 80526 RONALD A. RYDER, Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523 EUGENE DECKER, Department of Fishery and Wildlife Biology, Colorado State University, Fort Collins, CO 80523 Abstract: Responses of waterbirds to experimental disturbances were studied from April 1984 to August 1985 at Russell Lakes State Wildlife Area in the San Luis Valley, Colorado. Black-crowned night-herons (Nycticorax nycticorax), snowy egrets (Egrelta thula) and white-faced ibis (Plegadis chihi) were approached directly by a person on foot or in a motor vehicle. Mean (±SD) flushing distances for these species were 153±66, 93±43, and 95±48 m when approached on foot and 47±26, 57±27, and 54±27 m when approached in a motor vehicle. Reactions of American coots (Fulica americana), redheads (Aythya americana), ruddy ducks (O;ryura jamaicensis), mallards (Anas platyrhynchos), gadwalls (A. strepera) and American avocets (Recurvirostra americana) to disturbance were also quantified. Intensity of response was independent of agent of disturbances (i.e., person on foot or in vehicle) for all species. Disturbance reduced species diversity and abundance for up to one hour. American coots and avocets were only minimally impacted by the disturbance agents used. Key words: American avocet, American coot, black-crowned night-heron, Colorado, disturbance, gadwall, mallard, recreation, redhead, ruddy duck, snowy egret, waterbirds, white-faced ibis. As the number and area of wetlands in North America have declined, participation in nonconsumptive wildlife recreation has increased (Tyre and James 1971, Aney and Cowan 1975, Gray 1975, Fazio and Belli 1977, Shaw et al. 1978, Arthur 1979, More 1979, U.S. Dep. Inter. 1982, Boyle and Samson 1983). This trend is expected to continue, considering demographic trends in the United States (Yeosting and Burkhead 1973, Belli 1977). Wetlands may receive more nonconsumptive wildlife use than surrounding uplands because they support greater species diversity. Also, many wetland birds such as herons, egrets, ibis and waterfowl are relatively large and easy to observe, characteristics that attract nonconsumptive wildlife users (Gray 1975). Thus, the need to protect wetlands and, at the same time, provide additional viewing opportunity presents a management dilemma. This study was initiated in response to increased demand for nonconsumptive wildlife activities that may stress sensitive species in wetland habitats. Objectives were to: (1) measure the effects of two methods of public viewing on Ciconiiformes and (2) test a method of investigating the effects of recreation-related disturbances on marsh birds. This study was supported by the Colorado Division of Wildlife through the Nongame Checkoff Fund. Colorado State University provided assistance in design and statistical analysis. R. M. Bartmann and R. W. Hoffman reviewed the manuscript. lake bed bordered by the Sangre de Cristo Mountains on the east and the San Juan Mountains on the west. The mountain ranges meet at Poncha Pass to form the northern boundary of the valley. To the south the Valley extends into New Mexico. Elevations vary from 2,285 to 2,400 m with Russell Lakes at approximately 2,300 m. The average annual precipitation in Saguache, about ten kilometers north of the study area, was 26.8 cm from 1931 to 1960 (U.S. Dep. Commerce 1978). Although the climate of the San Luis Valley is arid, a high water table and irrigation run-off results in numerous shallow, alkaline lakes and marshes. Russell Lakes State Wildlife Area (SWA) consisted of six natural lakes and numerous human-made ponds. All wetlands received supplemental water from artesian wells. Vegetation of the valley floor is dominated by an association of black greasewood (Sarcobatus vermiculatus) rabbitbrush (C hrysothamnus spp.) and inland saltgrass (Distichiis stricta). Wetlands are dominated by hardstem bulrush (Scripus acutus), baltic rush (Juncus balticus), and common cattail (Typha latifolia). Baltic rush is the dominant emergent in water < 15 cm in depth. Hardstern bulrush is dominant in water from 15 to 150 cm in depth. l\lETHODS Flushing distances of black-crowned night-herons, white-faced ibis and snowy egrets were measured from April through June 1985. Groups of resting and feeding birds in the immediate vicinity of Russell Lakes SWA were located on clear calm mornings. Each group was approached at a slow, steady rate by either a person on foot or in a motor vehicle until the bird(s) nushed. The distance (± 2m) from the disturbance agent to where the bird(s) had flushed was STUDY AREA The study was conducted al Russell Lakes State Wildlife Area (37° 57'N, 106° 07'W) in the northern San Luis Valley, Colorado (Fig. 1). The San (uis Valley is a Oat, ancient 1Present address: Ci1y of Boulder Open Space, 1405 South Foothills Highway, Boulder, CO 80303. 52 1991. Proc. Issues and Technology in the Management of Impacted Western Wildlife. Thorne Ecol. Inst. 5:52-59. �j.. j,.. measured with a Leitz rangcfinder. Mean flushing distances between disturbance agents and species were compared using t tests. Disturbance trials were conducted during July 1984 and April-July 1985 in one portion of Russell Lakes SWA. During trials in 1984, American coots, redheads, ruddy ducks and mallards were counted immediately before and immediately after a disturbance and at fifteen-minute intervals for one hour following the disturbance. These four species were the most common on the test area. Other species also occurred in the area but their presence during trials was not dependable. The agent of disturbance was one person on foot for all trials and all responses of selected species were quantified (Table 1). In 1985 disturbance trials were modified to include two disturbance agents, two additional species and a count interval shortened to increase sample size. Disturbances were either a person on foot or in a motor vehicle. Disturbance agents traveled along a dike and returned at a slow, steady speed. Selected species were counted before the disturbance and at five-minute intervals for one hour after a disturbance from one of two elevated blinds that were entered out of view of the disturbance trial area. Responses were tested for independence with a chi-square test "'" Table 1. Quantification of marsh bird responses to disturbance. COLORAOO •DENVER eGRAND Ju-4CTION •PUEBLO F'ONCHA ~ ,t..J-. " J(:,. l>- 4:'.. " " . &\ "'~ ~"-A AA RIOGRAN Response values 0 1 2 3 4 00UITY ROAD R Response No obvious response Subjects watched disturbance Subjects swam away from disturbance Subjects "ran" on water or dove Subjects flew from wetland RESULTS Flushing Distance Snowy egrets flushed at distances of 93±43 m (n = 16) when approached on foot compared to 57± 27 m (n = 28) when approached in a motor vehicle. Flushing distances for white-faced ibis were nearly identical to those of snowy egrets, averaging 95±48 (n = 42) and 54± 27m (n = 14), respectively, when approached on foot or in a vehicle. Although sample sizes for black-crowned night-herons were small, mean flushing distance from a person on foot (153±66 m [n = 41) was greater than when approached in a vehicle (47±26 m [n = 21). Within a species, there was no difference (P ~ 0.25) in mean flushing distance between disturbance agents. Birds flushed nearly twice as far from a person on Coot, however, versus a person in a motor vehicle. Figure 1. Russell Lakes area, San Luis Valley, Colorado 53 �DISCUSSION Disturbance Trials American Coot- The number of American coots Flushing distances measured at Russell Lakes SW A supports the observation that wild animals are less disturbed by observers in motor vehicles than observers on foot (Schultz and Bailey 1978, Profera 1984). Due to small sample sizes and high variance, differences between disturbance agents used were not significant. Variance could be reduced in future studies with larger sample sizes for each agent of disturbance and species. Black-crowned night-herons were poorly represented in the samples, possibly because they feed after dark. Thus, flushing distances outside rookeries were difficult to obtain during daylight. It is possible that night-herons may be less vulnerable to human disturbance outside rookeries due to their nocturnal behavior. Group size of approached birds may have contributed to variance in flushing distances. Birds may tolerate approaching humans or vehicles because individuals feel more secure in groups than alone. Group size in future studies should be stratified into categories: I, 2-5, >5. etc. Group size was recorded in this study but small sample sizes precluded stratifying before analysis. Flushing distances varied more for a person on foot despite larger sample sizes for two of the three species tested with this disturbance agent. Ciconiiformes appeared to · be uniformly tolerant of vehicles but varied greatly in their tolerance of persons on foot. This could be related to the extent of habituation among individuals. Over tim~. responses to a person on foot may diminish due to habituation. Declines in species diversity following disturbances were detected in all trials despite varying responses among species. Mallards and gadwalls flushed and did not return during the following hour. In some tests, birds landed in the pond during the trial and were counted. It could not be determined, however, if these birds were the same individuals that had flushed. Marked birds in future studies would allow observers to identify individuals to ascertain when birds retwned after being flushed. The mean number of redheads, ruddy ducks, mallards and gadwalls on the test pond declined after disturbance regardless of agent. Mallards flew from the pond during a disturbance and did not return during the following hour. Gadwalls also flew from the pond during a disturbance, but returned to the pond during the following hour. Since birds were not marked, it could not be determined if the same individuals returned. American avocet numbers remained constant or increased slight.ly as other avocets landed in the pond after the disturbance. Avocets typically ignored the disturbance counted immediately after a disturbance in 1984 decreased to almost zero, but returned to pre-disturbance levels within 15 minutes (Table 2). Coots swam out of sight into hardstem bulrush stands (where they could not be counted) when disturbed. They remained hidden during the disturbance and began returning to open water after the disturbance ceased. Disturbances did not affect number of coots counted in 1985 (Tables 2 and 3). The difference between 1984 and 1985 count data was the result of coot behavior. In 1985, coots over 20 m from the disturbance swam from view and hid as they did in 1984. Coots in hardstem bulrush stands along the trail (before the disturbance) flushed into the open when disturbed. The intensity of coot responses was independent of the agent of disturbance (X 2 = 3.3, 0.25 < P < 0.50) (Fig.2). Redhead-The number of redheads counted immediately after disturbances decreased from pre-disturbance counts in 1984 and 1985 (Tables 2 and 3). During four trials redheads flew from the area or hid in hardstem bulrush. In these trials, redheads did not return to pre-disturbance activity (where they could be counted) during the following hour. In one trial, the number of redheads counted was unaffected by disturbance. Response values of redheads were independent of the agent of disturbance (X 2 = 2.15, 0.25 < P < 0.50) (Fig. 3). Ruddy Duck-The number of ruddy ducks counted on wetlands after a disturbance decreased from pre-disturbance \ levels in 1984 (Table 2). When disturbed, ruddy ducks dove into the water and probably resurfaced in the hardstem bulrush where they could not be counted. They began returning to open water during the hour after the disturbance. In 1985, the number of ruddy ducks decreased after the disturbance in all trials and did not return to pre-disturbance levels except in one case (Tables 2 and 3). Small sample size precluded statistical testing. Mallard-Mallards responded to disturbance by flying from the wetland and not returning during the hour following the disturbance in most Lrials (Tables 2 and 3). The post-disturbance number returned to pre-disturbance levels within one hour in three trials in 1985. Small sample size precluded statistical testing. Gadwall-The mean number of gadwalls counted in the test area decreased immediately after a disturbance in 13 of the 20 trials (Tables 2 and 3). In most trials, the number of gadwalls returned to pre-disturbance levels within one hour. There was no difference in gadwall responses to the two disturbance agents (X 2 = 3.22, 0.50 < P < 0.75) (Fig. 4). used. American A vocet-Neither agent of disturbance had an effect on American avocets (Tables 2 and 3). Response values were low and did not depend on disturbance agent (X2 = 1.18, 0.50 < P < 0.75) (Fig. 5). American coots and diving ducks (redheads and ruddy ducks) temporarily hid in the bulrush or dove in response to disturbance. American coot numbers returned to pre- 54 �A 70 A (13) 60 (11) so - ':'.:-»: 50 40 - 40 30 - 30 >z Ili'il : 20 - 20 0 (6) (5) 10 >- (1) w !!!! 10 - 0 zw ::) aw 0 - - 4 - -....., _ ::) a: aw 8 LL a: (8) 50 50 - Itf ·········· (6) 111!1 :-:❖:•: I 40 - 1 1 =~t~=~= ll!i!I! .• •. ::::::::: 1 ~11~1-..----.2 (5) (4) li 1 20 - ~ --'--~ ' ~ ) '------L!!-1111~! 0 1 (7) 30 :: 111111 8 LL 60 : i _ _,,_--"-t:..:l=i:_ _.__,i-J--___._,_m .,.. l\f..... 1 111!. 3 Q 4 {{: --L...-..,.. l -----.:.;,...._ 1 ____._-'-'-,l~ -....I -......L:;;.;,;. l :..L..- Q RESPONSE VALUE 1 2 3 4 RESPONSE VALUE Figure 2. Frequency of American coot responses to (A) a person on foot and (B) in a motor vehicle during disturbance trials in 1985. Figure 3. Frequency of redhead responses to (A) a person on foot and (B) in a motor vehicle during disturbance trials in 1985. 55 �A A (9) 50 60 40 (7) 50 30 :: 20 >() z Jil::::::::: 20 !_I.I.I.I. 1 10 ii >- 10 (1) 1!111!1 ( ) 0 -+--~-.a..:.:.;.;"'----'-'-..,__.___,_.:.:,.;.:.&_.&.:.:.,:.~ () z w :::> LU :::, aLU (5) aUJ 8 cc a: LL LL 8 80 70 (7} ii I (1) 10 :{lll: 0 _.___....._r-L-___.""'r-'------,.---.------L~10 2 1 3 4 2 0 1 2 3 4 RESPONSE VALUE 0 : (::.:_:·2:_·.:i·:_ :__:::::::::·: RESPONSE VALUE Figure 4. Frequency of gadwall _-responses to (A) a person on foot and (8) in a motor vehicle during disturbance trials in 1985. Figure 5. Frequency of American avocet responses to (A) a person on foot and (B) in a motor vehicle during disturbance trials in 1985. · 56 �Table 2. Marsh birds on a wetland immediately before, after, and at 15-minute intervals for one hour after disturbance by a person walking. n present Species Year Post-disturbance (min.) n counts After disturbance 15 30 45 60 3-29 16 15.3 10.5 0-2 0 0.5 0.8 4-23 17.5 14.8 7.6 2-40 22.5 21.8 12.9 6-31 26.5 23.3 9.3 3-36 26.5 23.0 10.9 5-22 10.5 11.6 5.0 5-20 10.0 11.4 3.4 2-18 8.5 9.4 4.5 3-26 9.0 10.3 6.0 4-21 10.5 11.7 5.3 4-25 11.6 5.9 1-5 3.0 2.8 1.5 0-3 0.0 1.0 1.4 0-1 1.0 0.8 0.5 0-4 2.0 1.8 1.5 0-6 1.0 2.4 2.9 0-5 1.0 2.0 2.0 2-17 7.0 7.5 4_4 · 0-14 6.0 6.6 4.4 0-11 6.0 5.5 4.0 0-13 3.0 4.8 4.7 0-13 6.0 6.4 4.7 0-16 3.0 4.8 4.9 1-12 2.0 4.4 4.0 0-2 1.0 1.0 1.0 2-12 3.0 4.7 3.7 2-10 3.0 4.4 3.0 0-7 4.0 3.7 2.5 0-10 2.0 2.7 3.4 1-4 1.0 1.8 1.5 0-1 0.0 0.3 0.5 0 0.0 0.0 0 0.0 0.0 0-3 0.5 1.0 1.4 0-6 1-11 9.0 7.5 4.7 0-2 0.5 0.8 1.0 0-3 1.0 1.3 1.3 0-3 0.5 1.0 1.4 0-3 1.0 1.3 1.5 0-4 1.0 1.5 1.7 1-5 2.0 2.3 1.1 0-2 0.0 0.6 0.9 0-2 0.0 0.3 0.7 0-1 0.0 0.4 0.5 0-2 0.0 0.8 1.0 0-2 0.0 1-10 5.0 5.3 3.0 0-6 2.0 2.7 2.5 0-8 2.0 2.7 3.0 0-8 1.0 2.2 3.1 0-12 3.0 4.2 3.8 0-9 2.0 3.3 3.6 1-4 2.0 2.3 1.1 0-4 2.0 2.1 1.1 0-5 2.0 1.9 1.4 0-6 2.0 2.2 1.7 0-4 2.0 1.9 1.2 0-8 2.5 2.9 2.5 Before disturbance American coot 1984 6 Range Median i SD 1985 16 Range Median i SD Redhead 1984 5 Range Median i SD 1985 21 Range Median i SD Ruddy duck 1984 7 Range Median i SD 1985 4 Range Median i SD Mallard 1984 i SD 9 Range Median i SD Gadwall 1985 i SD American avocet Range Median i SD 0.6 0.7 IO Range Median 1985 0.0 1.5 3.0 4 Range Median 1985 9.5 12 57 �... Table 3. Marsh birds on a wetland immediately before, after, and at 15-minute intervals for one hour after disturbance by a motor vehicle, 1985. n present Before disturbance American coot Range Median Range Median i SD 3-17 9.0 9.5 3.9 4-15 8.0 8.6 3.7 3-16 10.0 9.1 3.9 3-19 8.0 8.5 4.4 3-18 8.0 8.6 4.7 2-12 7.0 7.2 3.6 0-14 7.0 7.0 5.5 0-11 7.0 6.1 4.0 0-12 4.0 4.9 4.4 0-12 3.0 4.9 4.5 0-12 4.0 4.5 4.2 1-3 2.0 2.0 1.4 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 0 0.0 0.0 1-13 7.0 7.0 8.5 1-6 3.5 3.5 3.5 0-6 3.0 3.0 4.2 2-5 3.5 3.5 2.1 2-4 3.0 3.0 1.4 3-4 3.5 3.5 0.7 1-8 3 .5 3.4 2.0 0-9 2.0 2.1 2.8 0-3 1.0 1.1 1.2 0-5 1.0 1.5 1.8 0-6 3.0 2.9 2.4 0-7 2.0 2.4 2.6 1-5 3/0 3 .1 1.5 1-4 2.0 2.4 1.3 0-5 2.0 2.4 1.7 0-6 2.0 2.1 2.2 0-5 0-14 3.0 2.6 1. 7 3.0 4.3 10 i SD American avocet 4-18 9.0 9.1 3.5 2 i SD Gadwall Range Median 60 2 i SD Mallard Range Median Post-disturbance (min.) 30 45 13 i SD Ruddy duck Range Median 15 14 i SD Redhead Range Median After disturbance 7 4.7 birds to human disturbance should be periodically measured to learn if habituation occurs with increased exposure to human activities. Natural resource managers, when planning wildlife viewing opponunities in wetlands, should consider that the intensity of responses of waterbirds to recreationrelated disturbance will vary among species and agents of disturbance . disturbance levels within one hour. In 1984, the mean number of coots on the test pond one hour after a disturbance exceeded the pre-disturbance number. This can be explained by blind placement. Blind placement in 1984 did not allow birds to be counted in a small area near the dike along which the disturbance occurred. During many trials, coots were obscured from view prior to disturbance. When disturbed, they swam across the pond and were counted. They did not return to the original area during the following hour. Blind placement the following year allowed all birds on the pond outside of the bulrush area to be counted. LITERATURE CITED Aney, W. W., and C. D. Cowan. 1975. Survey shows wildlife important recrca1ional resource. Oregon Wild!. 30(2):8-9. Arthur, L. M. 1979. The aesthetic value of wildlife: perceptions of the American public and sportsmen. Pages 32-34 in T. C. Daniel, E. H. Zube, and B. L. Driver, eds. Accessing amenity resource values. U.S. Dep. Agric., For. Serv. Gen. Tech. Rep. RM-68. Belli, L. A. 1977. Survey of nonconsumptive wildlife users in Idaho. M.S. Thesis. Univ. Idaho, Moscow. 110 pp. Royle, S. A., and F. B. Samson. Nonconsumptive outdoor recreation; an annotated bibliography of human wildlife interactions. U.S. Dep. Imer., Fish and Wild!. Serv. Spec. Sci. Rep. 252. 113 pp. MANAGEMENT IMPLICATIONS Managers planning for visitors at wetlands should identify the species present and their potential responses to visitor-induced disturbance. Disturbance trials proved to be useful for measuring species responses. -Viewing from motor vehicles would cause less disturbance to wildlife while restricting visitors to designated routes. Responses of water- 58 �Fazio, J. R., and L. A. Belli. 1977. Characteristics of nonconsumptive wildlife users in Idaho. Trans. Norlh Am. Wildl. and Nat. Resour. Conf. 42:117-128. Gray, G. C. 1975. Nonconsumptive demand for wildlife by municipal conservation commissioners in Massachusetts. M.S. Thesis, Univ. Massachusells, Amherst. 94 pp. More, T. A. 1979. The demand for nonconsumptive wildlife users: a review of the literature. U.S. Dep. Agric., For. Serv. Gen. Tech. Rep. NE-52. 16 pp. Profera, J. 1984. Development of sage grouse public viewing tours, North Park, Colorado. Colorado Div. Wildl., Wildl. Res. Rep. 2:373-386. Schultz, R. D., and J. A. Bailey. 1978. Responses of national park elk to human activity. J. Wild!. Manage. 42:91-100. Shaw, W. W., D. J. Willer, D. A. King, and M. T. Richards. 1978. Nonhunting wildlife enthusiasts and wildlife management. Proc. West. Assoc. Fish and Wildl. Agencies 58:255-263. Tyre, G. L., and G. A. James. 1971. Length and rate of individual participation in various activities on recreation sites and areas. U.S. Dep. Agric., For. Serv. Res. Note. SE161. 4 pp. U.S. Department of Commerce. 1978. Climates of the United States. Gales Res. Co., Detroit, Mich. 606 pp. U.S. Department of Interior. 1982. 1980 National survey of fishing, hunting and wildlife-associated recreation. U.S. Dep. Inter., Fish and Wild!. Serv., ·Washington D.C. 156 pp. Yeosting, D. R .• and D. L. Burkhead. 1973. Significance of childhood recreation experience on adult leisure behavior: an exploratory analysis. J. Leisure Res. 5:25-36. 59 � Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Journal Articles Description An account of the resource CPW peer-reviewed journal publications Text A resource consisting primarily of words for reading. Examples include books, letters, dissertations, poems, newspapers, articles, archives of mailing lists. Note that facsimiles or images of texts are still of the genre Text. Dublin Core The Dublin Core metadata element set is common to all Omeka records, including items, files, and collections. For more information see, http://dublincore.org/documents/dces/. Title A name given to the resource Response of waterbirds to experimental disturbances Description An account of the resource <p>Responses of waterbirds to experimental disturbances were studied from April 1984 to August 1985 at Russell Lakes State Wildlife Area in the San Luis Valley, Colorado. Black-crowned night-herons (<em>Nycticorax nycticorax</em>), snowy egrets (<em>Egretta thula</em>) and white-faced ibis (<em>Plegadis chihi</em>) were approached directly by a person on foot or in a motor vehicle. Mean (±SD) flushing distances for these species were 153±66, 93±43, and 95±48 m when approached on foot and 47±26, 57±27, and 54±27 m when approached in a motor vehicle. Reactions of American coots (<em>Fulica americana</em>), redheads (<em>Aythya americana</em>), ruddy ducks (<em>O ura jamaicensis</em>), mallards (<em>Anas platyrhynchos</em>), gadwalls (<em>A. strepera</em>) and American avocets (<em>Recurviroslra americana</em>) to disturbance were also quantified. Intensity of response was independent of agent of disturbances (i.e., person on foot or in vehicle) for all species. Disturbance reduced species diversity and abundance for up to one hour. American coots and avocets were only minimally impacted by the disturbance agents used.</p> Bibliographic Citation A bibliographic reference for the resource. Recommended practice is to include sufficient bibliographic detail to identify the resource as unambiguously as possible. George, J. L., C. E. Braun, R. A. Ryder, and E. Decker. 1991. Response of waterbirds to experimental disturbances. Proceedings V. Issues and Technology in the Management of Impacted Wildlife 5:52–59. Creator An entity primarily responsible for making the resource George, Janet L. Braun, Clait E. Ryder, Ronald A. Decker, Eugene Subject The topic of the resource American avocet American coot Black-crowned night-heron Colorado Disturbance Gadwall Mallard Recreation Redhead Ruddy duck Snowy egret Waterbirds White-faced ibis Extent The size or duration of the resource. 8 pages Date Created Date of creation of the resource. 1991 Rights Information about rights held in and over the resource <a href="http://rightsstatements.org/vocab/InC-NC/1.0/" target="_blank" rel="noreferrer noopener">In Copyright - Non-Commercial Use Permitted</a> Format The file format, physical medium, or dimensions of the resource application/pdf Language A language of the resource English Is Part Of A related resource in which the described resource is physically or logically included. Issues and technology in the management of impacted wildlife : proceedings of a national symposium, Snowmass Resort, Colorado, April 8-10, 1991 Type The nature or genre of the resource Article