USE of PREDATOR EXCLOSURES to PROTECT PIPING PLOVER NESTS in ALBERTA and SASKATCHEWAN 2000 Field Season Report Lance Engley
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USE OF PREDATOR EXCLOSURES TO PROTECT PIPING PLOVER NESTS IN ALBERTA AND SASKATCHEWAN 2000 Field Season Report Lance Engley and Isabelle Michaud In cooperation with: Alberta Environment, Fisheries and Wildlife Management Division Alberta Sport, Recreation, Parks & Wildlife Foundation Canadian Wildlife Service North American Waterfowl Management Plan World Wildlife Fund ACKNOWLEDGEMENTS Thank you to the agencies whose generous funding made this project possible: Alberta Conservation Association, Alberta Sport, Recreation, Parks & Wildlife Foundation, Alberta Environment, Fisheries and Wildlife Management Division, North American Waterfowl Management Plan, and World Wildlife Fund. Thank you to everyone (in alphabetical order) that contributed to the project through time in the field, sitting in meetings, building exclosures, sharing ideas or contributing data: Ron Bjorge, Steve Brechtel, Gordon Court, Paul Goossen, Ed Hofman, Dave Moore, Dave Prescott, Tom Sadler, and Gary Walsh. Finally, thank you to the field staff, Jeff Adamyk, Sherry Feser, Greg McClelland, Camila Morcos, Mark Piorecky, and Roy Schmelzeisen for all their hard work and long hours in the field. i TABLE OF CONTENTS ACKNOWLEDGEMENTS............................................................................................................. i INTRODUCTION .......................................................................................................................... 1 STUDY AREA AND METHODS ................................................................................................. 1 RESULTS ....................................................................................................................................... 3 DISCUSSION................................................................................................................................. 6 LITERATURE CITED ................................................................................................................... 8 APPENDIX 1. Maps of nesting sites on study lakes................................................................... 10 APPENDIX 2. Original data from 2000 field season.................................................................. 11 LIST OF FIGURES Figure 1. Map of study area, 2000. ................................................................................................ 2 Figure 2. Trend in the population of Piping Plovers on nine key breeding lakes in Alberta......... 5 Figure 3. Location of Piping Plover nests on Birch Lake in 2000.............. Error! Bookmark not defined. Figure 4. Location of Piping Plover nests on Cipher Lake in 2000............ Error! Bookmark not defined. Figure 5. Location of Piping Plover nests on Chain Lake #4 in 2000........ Error! Bookmark not defined. Figure 6. Location of Piping Plover nests on Freshwater Lake in 2000..... Error! Bookmark not defined. Figure 7. Location of Piping Plover nests on Sunken Lake in 2000........... Error! Bookmark not defined. Figure 8. Location of Piping Plover nests on Dowling Lake in 2000......... Error! Bookmark not defined. Figure 9. Location of Piping Plover nests on Killarney Lake in 2000. ...... Error! Bookmark not defined. Figure 10. Location of Piping Plover nests on Metiskow Lake in 2000..... Error! Bookmark not defined. Figure 11. Location of Piping Plover nests on Handhills Lake in 2000..... Error! Bookmark not defined. Figure 12. Location of Piping Plover nests on Piper Lake in 2000. ........... Error! Bookmark not defined. Figure 13. Location of Piping Plover nests on West Reflex Lake in 2000. Error! Bookmark not defined. LIST OF TABLES ii Table 1. Nest summaries for study lakes ....................................................................................... 3 Table 2. Summary of banding in 2000........................................................................................... 4 Table 3. Summary of 2000 adult and brood surveys ..................................................................... 4 Table 4. Number of adult Piping Plovers observed on selected Alberta lakes between 1986 and 2000.................................................................................................................................. 5 iii INTRODUCTION The Piping Plover is designated as 'endangered' in Canada, 'threatened' in the U.S. (COSEWIC 2000, U.S. Fish and Wildlife Service 2000) and is listed as 'endangered' under the Alberta Wildlife Act. Nest predation has been identified as a significant limiting factor to Piping Plover reproductive success in the Great Plains (Whyte 1985, Haig 1992, Heckbert 1994, Richardson 1999). Results from studies carried out in east-central Alberta from 1995 to 1997 showed that through the use of predator exclosures, Piping Plover nest predation can be significantly reduced thus increasing productivity (Heckbert and Cantelon 1996, Richardson 1999). Consequently, a management project implementing the use of predator exclosures on a large-scale basis was initiated in Alberta in 1998 and is ongoing. STUDY AREA AND METHODS The predator exclosures used in the 2000 field season were circular in shape, made of a single length of stucco wire approximately 9 m long and 1.2 m high. The two ends of the stucco wire were attached with a 1.5 m length of re-bar, woven through the wire where it overlappped, creating an exclosure approximately 3 m in diameter. Four additional pieces of re-bar were attached to the exclosure at even intervals and inserted into the substrate for stabilization. In an effort to prevent birds from perching on the exclosures, the horizontal wire along the top of the exclosure was removed in order to expose the vertical wires. The bottom of each exclosure was secured in place by using 10 cm nails, bent at the top. To protect against aerial predators, the tops were covered with 2 cm x 2 cm plastic mesh, secured with 10 cm long cable ties. Smaller exclosures, used in previous field seasons (e.g., Michaud and Prescott 1999, Richardson 1999) were applied to nests on Birch Lake. These exclosures were square-pyramidal in shape, made of four stucco wire panels with bottom width of 1.2 m and top width of 60 cm. The four panels were attached together with hog clips. The exclosures were supported by four-1.5 m pieces of re-bar attached to each corner and driven into the ground for stabilization. The bottom of each exclosure was secured in place by inserting two-10 cm nails, bent at the top, into the ground on each of the four sides. Finally, to guard against aerial predators, the top was woven with bailing twine at 10 to 15 cm intervals. Beginning in early May, potential breeding lakes were surveyed for returning Piping Plovers. In order to maximize the efforts of the researchers, only lakes with easy access and relatively large Piping Plover populations were included in the management initiative. Twelve waterbodies were divided into three study areas based on geographic location. Lakes in the east-central part of the province (Figure 1) included: the westernmost of the Reflex Lakes (hereafter called Reflex Lake), Killarney Lake, Freshwater Lake, Cipher Lake, 'Piper Lake', Metiskow Lake and Sunken Lake. In the Hanna area surveyed lakes were: Little Fish Lake, Handhills Lake, Dowling Lake and 'Chain Lake #4'. Birch Lake near Vermilion was also included. Pair and brood surveys were carried out on all 12 lakes: Most of these lakes have been surveyed annually since 1989 and some since 1986. Pair surveys were carried out from 25 May to 7 June and brood surveys were carried out from 3 to 11 July. Lakes were surveyed on foot by walking approximately 60 to 70% of the way between the water and the vegetation line and stopping periodically to scan for plovers. Location of adults and juveniles were recorded and mapped. 1 Birch Edmonton # Wainwright Cipher Reflex ## Killarney # # Metiskow # # Sunken # Freshwater Piper Red Deer Chain #4 # # Dowling # Handhills Oyen Drumheller # Little Fish Calgary Brooks Medicine Hat Lethbridge 30 0 30 60 Kilometers Figure 1. Map of study area, 2000. 2 Census, exclosure application, and monitoring techniques followed the procedures outlined by Richardson (1997). For nests that had exclosures applied, they were erected within one day of discovery, regardless of the stage of incubation. Two researchers carried the exclosure to the nest and secured it to the substrate with the five re-bars and the bent nails. After application, each nest was monitored from 70 to 100 m away until the adults resumed incubation. Enclosed nests were monitored every second or third day throughout the incubation period. Changes in nest status were noted including predation of eggs, predation of adult(s), unexplained abandonments and hatching. Traditional nest success was calculated by dividing the number of successful nests (those hatching at least one chick) by the total number of nests for each lake. RESULTS A total of 58 nests were found on 11 waterbodies (Table 1). Overall hatching success (those nests hatching at least one egg) was 60% (35/58). Nests that were treated with exclosures for either part or all of the incubation period hatched 22 of 35 nests (63%). The twenty-three nests treated with large predator exclosures for the entire incubation period had 48% (11/23) hatching success. Of the 12 nests where large exclosures were applied and then removed during incubation, 92% (11/12) were successful. For nests where exclosures were not applied at all, 53% (10/19) were successful. On Birch lake, where small predator exclosures