In 2022, we monitored the Western Snowy Plover (WSP) population at Coal Oil Point Reserve as in previous years. The number of breeding adults was 52, higher than the average of 37 for our site. The wintering population size was 183, also above the average of 167. Skunk predation was the primary cause of nest failure. In response to the high levels of predation by skunks and the failure to trap them, all nests present on or laid after April 29th and before May 31st were collected, incubated until near the hatching date, and then returned to the parents. The real eggs were replaced with wooden eggs so that the parents would continue incubating. 35 nests (34%) of nests this season were replaced using this method. The hatching and fledging success rates in this report reflect those that hatched and fledged naturally and exclude nests that had eggs replaced. Hatching rate (28%) was lower than average (53%) and the fledging rate (74%) was higher than average (62%). The number of fledged chicks per male (1.0) met our site's recovery goal of 1.0 fledged chicks per male. 92% of nests (94) were initiated on the beach, and 8% (8) were initiated on the mudflats of the slough (delta).
In 2021, we continued with the monitoring of the Western Snowy Plover (WSP) population at Coal OilPoint Reserve as in previous years. The number of breeding adults this year (56) was higher than theaverage (37) for our site. The wintering population size (175) was just over the average (167). This year,predation was the primary cause of nest failure. There were three cases of take by people on Sands Beach. The eggs from 3 nests were removed and in 2 of the nests that had exclosures, the exclosure wasremoved and vandalized. Implementation of Australian crow traps this year prevented crow predation.However, one quarter of all nests were predated by skunks and an additional 8% were lost to unknownpredators. In response to the high levels of predation by skunks, all nests present on or laid after July 13thwere collected, incubated until near the hatching date, and then returned to the parents. The real eggswere replaced with wooden eggs so that the parents would continue incubating. COPR had a lower thanaverage hatching rate (35%) and a high fledging rate (72%) (this analysis excludes the 8 out of 8 neststhat hatched with the egg replacement technique). The number of fledged chicks per male (1.5) was belowaverage for our site but exceeded our site's recovery goal of 1.0 fledged chicks per male. 99% of nests(92) were initiated on the beach, and 1% (1) were initiated on the mudflats of the slough (delta).
In 2020, we continued with the monitoring of the Western Snowy Plover (WSP) population at Coal Oil Point Reserve as in previous years. The number of breeding adults this year (51) was higher than the average (36) for our site. The wintering population size (34) was the lowest on record since monitoring began at COPR in 2001. This year, one fifth of all nests were washed out by high tides. Wind and predation by crows also had a large impact on the fate of nests and chicks. In early April, we implemented the use of predator exclosures to prevent further predation of nests by crows. While COPR had a higher than average hatching rate (55%), predation on chicks by gulls and crows resulted in a low fledging rate of 38%. The number of fledged chicks per male (0.9) was less than half the average for our site. 91% of nests (69) were initiated on the beach, and 9% (7) were initiated on the mudflats of the slough (delta).
In 2019, we continued with the monitoring of the Western Snowy Plover (WSP) population at Coal Oil Point Reserve as in previous years. The number of breeding adults (68) was the highest observed since monitoring began in 2001. The wintering population (132) was below the average for this site. This year, predation, particularly by crows, had a large impact on the fate of nests and chicks, as did high tides. The rate of fledged chicks per male (0.2) was the lowest on record for our site since the program began in 2001. 96% of nests (93) were initiated on the beach, and 4% (4) were initiated on the mudflats of theslough (delta).
In 2018, we continued with the monitoring of the Western Snowy Plover population at Coal Oil Point Reserve as in previous years. The number of breeding adults (54), hatched nests (61), and fledged chicks (82) were the highest observed since monitoring began in 2001. The wintering population remained around the average (182) for this site. This year, predation affected nest fate slightly more than weather. 86% of nests were initiated on the beach, and 14% were initiated on the mudflats of the slough (delta). The rate of infertile eggs has returned to normal levels after an four-fold increase in infertility in 2016.
In 2017, we continued with the monitoring of the Western Snowy Plover population at Coal Oil Point Reserve as in previous years. The count of wintering plovers was the second lowest recorded since monitoring began in 2001. The breeding population remained stable at approximately 20 pairs and the number of chicks that fledged was higher than average. This year, weather affected nest fate more than predation. The rate of infertile eggs was higher than average. All plover nesting activity occurred on the beach. For the first time since 2007, there were no nests on the mudflats of the slough.
In 2015, we continued with the monitoring of the WSP population at Coal Oil Point Reserve as in previous years. This year's chick fledge count was higher than average. Nest predation by skunks was a problem until predator control was initiated in early May. The rate of infertile eggs was higher than average. Nesting activity on the mudflats was the lowest it has been since 2007.
In 2016, we continued with the monitoring of the WSP population at Coal Oil Point Reserve as in previous years. The count of wintering plovers was the lowest ever recorded since monitoring began in 2001. This year, the number of chicks that fledged was higher than average. Nest predation by skunks was a problem until predator control was initiated in late March. The rate of infertile eggs was higher than average. Nesting activity on the mudflats was low.
In 2014 we continued with the monitoring of the WSP population at Coal Oil Point Reserve as in previous years. We had predator control during most of the breeding season, but nest predation by mammalian predators was high. However, chick fledge rates were higher than average. Nesting on the mud flats was also the highest on record.
