SHORT COMMUNICATIONS 685 SAVARD, J.-P. L. 1984. Territorial behavior of Common Goldeneye, Barrow’s Goldeneye, and Bufflehead in areas of sympatry. Omis Stand. 15211-216. SEYMOUR,N. R. ANDR. D. TITMAN. 1978. Changesin activity patterns,agonistic behavior, and territoriality of Black Ducks (Anus rubripes)during the breeding seasonin a Nova Scotia tidal marsh. Can. J. Zool. 56:1773-1785. TOME, M. W. 1984. Changesin nutrient reservesand organ size of female Ruddy Ducks breeding in Manitoba. Auk 101:830-837. -. 199 1. Diurnal activity budget of female Ruddy Ducks breeding in Manitoba. Wilson Bull. 103:183-189. WIENS,J. A., S. G. MARTIN, W. R. HOLTHAUS,AND F. A. IWEN. 1970. Metronome timing in behavioral ecology studies. Ecology 51:350-352. ZICUS,M. C. 1989. Automatic trap for waterfowl using nest boxes. J. Field Omithol. 60: 109-111. MICHAELC. ZICUS AND STEVEN K. HENNES, Wetland Wildlife Populationsand Research Group, Minnesota Dept. of Natural Resources,102 23rd St., Bemia!ji, Minnesota 56601. (Presentaddress of SKH: 2065 W. CountyRd. E, New Brighton,Minnesota 55112). Received 9 Feb. 1993, acceptedI6 June 1993. Wilson Bull., 105(4), 1993, pp. 685-687 Rapid colonization of a human-made wetland by Mariana Common Moorhen on Guam. - The Mariana subspeciesof the Common Moorhen (Gallinula chloropusguami) is endemic to the Mariana Islands in the western Pacific Ocean and is endangered(USFWS 1984). Current populations are found on the islands of Guam, Tinian, and Saipan which support an estimated 100-125, 75, and 100 moorhens, respectively, (Stinson et al. 1990). Degra- dation and lossof natural wetlands have contributed to the decline of the species,but human- made sites on Guam have supplemented available habitat (USFWS 1984, Stinson et al. 1990). In 1987 and 1988, about 80% of all wetlands used by moorhens during the wet and dry seasonswere artificial (Stinsonet al. 1990). Many ofthese sitesoriginally were constructed as aquaculture ponds, ponding basins for flood control, reservoirs for municipal use and livestock, or as scenic ponds on golf courses.They provide nesting and foraging areas for moorhens after suitableaquatic vegetationbecomes established. However, many are subject to severe inundation and drying out in responseto seasonalrainfall patterns (M. Ritter, unpubl. data). Since 1985, a dramatic increase in large tourist-related developments has resulted in increased conflicts over wetlands between developers and natural resource management agencies.Conflicts often associatedwith developments are mitigation, run-off control, ero- sion control, improved aesthetics,and providing higher wildlife values. On the Manengon Hills Resort, project planners and biologists identified a unique opportunity to integrate both the habitat requirements of moorhens with the design constraints and needs of de- velopment-based wetlands into aestheticand functional wetlands that would benefit moor- hens. This report documents the results of the first attempts by a land developer to build wetland habitat for Common Moorhens on Guam. We describethe constructionof a wetland and its rapid colonization by moorhens. The Manengon Hills Resort is located in south-centralGuam and covers 53 1 ha. It is the largest tourist development on the island and will have 3000 housing units, a hotel, a 45- hole golf course, and associatedrecreational and shopping facilities when completed. The existing watershedsare being maintained, but much of the existing upland grasslandshave 686 THE WILSON BULLETIN l Vol. 105, No. 4, December1993 TABLE 1 WETLAND PLANTS AT WETLAND 52M AND THEIR PERCENT OF COVERAGE IN JANUARY 1993 Spikerush (Eleocharisdulcis) 60% Fringe rush (Fimbristylis littoralis) 10% Rusty flatsedge (Cyperusodoratus) < 1% Tall fringe rush (Fimbristylis dichotoma) < 1% Umbrella-grass (Fuirena umbellata) (1% False loosestrife (Ludwigia hyssopifolia) (1% Taro (Colocasiaesculenta) 0 Water lettuce (Pistia stratiotespb 0 n Wetland plantsintroduced in January 1992. b All plantswere hand-removed in early June 1992. been removed. Developers of the project agreed to build about 50 wetlands on the property as part of a mitigation plan to benefit moorhens. Two types of wetlands were constructed: on-slope and detention ponds. On-slope wetlands are constructed in the lower portions of natural valleys, and detention ponds are located near, and connected hydrologically to, existing on-site wetlands. The wetland of interest, 52M, is classified as an on-slope wetland. The wetland was built near several golf tees, a golf cart path, and a two-lane roadway. Construction of the wetlands’ basin was commenced and completed in January 1992. A medium-sized excavator was used to grade and slope the sides and bottom of the basin. The wetland is triangular in shape and is 600 mz in size. It is 45 m long and 27 m across at the widest point and surrounded by a short (30-45 cm high) rock and mortar wall. At the time of construction, the bottom soils were saturated and compaction was not feasible. The bottom of the ponded area was lined with a layer of hydric soil approximately 30 cm deep using the same excavator that performed the wetland shaping. Tamping with the back of the bucket of the excavator was done to shape and compact the hydric soil blanket. The soil was obtained from displaced wetlands elsewhere on the resort. About 90% of the wetland is shallow (20 cm deep), with a somewhat circular, deeper area (60 cm deep) located in the south-central portion of the wetland. Groundwater seepage out of the slope and stormwater runoff via surface and pipe flow provide recharge. Discharge is controlled by a vertical 30- cm-diameter polyethylene riser located near the south end. Five plant species were introduced into the wetland soon after construction was completed in January (Table 1). Spikerush (Eleocharisd&is) was planted on 46-cm centers in three groups, each containing approximately 40 plantings, on the east, west, and north sides of the deep water area. Water lettuce (Pistiu strutiotes)was placed along the southwestern edge of the pond and initially covered 5% of the surface area. In mid-February, taro (Colocasiu esculenta)was planted on 0.9 m centers in two groups, each with 10 plants, along the northern edge and in the water lettuce bed. In April, one or two plantings of rusty flatsedge (Cyperusodoratus) were also introduced into the wetland. By late April, spikerush covered 10% of the pond, but all taro had died, presumably because of excessive flooding. In early June, all water lettuce was hand-removed because it was rapidly expanding its range and encroaching into the stands of spikerush. At the time ofremoval, water lettuce had expanded to cover about 20% of the ponded surface area. As of January 1993, 75% of the ponded area was vegetated (Table 1). Species not initially introduced (i.e., fringe rush, Fimbristylis SHORT COMMUNICATIONS 687 littoralis; tall fringe rush, F. dichotoma; umbrella-grass, Fuirena umbellata; false loosestrife, Ludwigia hyssopifolia) may have come from the seed banks or propogated vegetatively from the existing or hydric soils. Sightings of moorhen chicks and adults by golf course personnel began in August, with at least four chicks seen on several occasions. Chicks were reported to have black natal down, indicating their age to be between a few days and four weeks. Three nests were found in early September several days after strong winds from Typhoon Omar on August 28 disrupted the vegetation and enhanced visual observation. One nest was in each of three original clumps of spikerush. Moorhens may build more than one brood nest (Wood 1974), and it is possible that this occurred here. Accounting for the age of the chicks and an incubation period of 22 days (Byrd and Zeillemaker 1981) nest construction probably occurred in early July. This suggests that Wetland 52M was colonized by the adult birds by at least June, which would have been only about five months after the wetland was first flooded. On October 6, we visited the site and observed one juvenile moorhen. On 6 January 1993, two moorhen in adult plumage were observed at the wetland. From the time of hatching, it takes 22 weeks for moorhens to attain adult plumage. Therefore, it is unknown if one or both of these birds were the breeding adults or chicks that had hatched in August. Moorhens probably colonized Wetland 52M from one of two existing wetlands to the north. Both are human-made and vegetated predominantly with spikerush. The larger wet- land (1 ha) is 750 m north, and the smaller (0.5 ha) is 1400 m northeast of Wetland 52M (Wiles and Ritter, in press). A few moorhens and their nests have been recorded regularly at both of these wetlands since 1972. These records offer some evidence that the adult birds observed at Wetland 52M may have originally come from one of these two wetlands. They also indicate that created wetlands can provide an important resource for this endangered subspecies. Acknowledgments. -Funding was provided by the U.S. Fish and Wildlife Services through the Federal Aid to Wildlife Restoration Program FW-2R. Special thanks go to G. J. Wiles for editorial assistance and to R. D. Anderson for useful comments. LITERATURE CITED BYRD, G. V. AND C. F. ZEILLEMAKER. 1981. Ecology of nesting Hawaiian Common Gal- linules at Hanalei, Hawaii. Western Birds 12: 105-l 16. STIN~ON, D. M., M. W. RI~XR, AND J. D. REICHEL. 1990. The Mariana Common Moorhen: decline of an island endemic. Condor 93:38-43. U.S. FISH AND WILDLIFE SERVICE. 1984. Nine Mariana Islands species listed as endangered. Endang. Spec. Tech. Bull. 9(9):1, 5-6. WILES, G. J. AND M. W. RIT~ER. Guam. in Oceania wetland survey, World Conservation Union, Gland, Switzerland. (in press). WOOD, N. A. 1974. The breeding behavior and biology of the Moorhen. British Birds 67: 104-115. 137-158. MICHAEL W. RITTER, Division of Aquatic and Wildrife Resources, P.O.