On August 2017, I observed a Northern Goshawk (Accipiter gentilis) wearing an anklet at Mizumoto Park, Tokyo. Thereafter, I observed such a goshawk eleven times until early April 2018. In all records, the observed individual was a juvenile. Characteristics of plumage and the presence of an anklet suggested that all eleven observation records were derived from one or a few individuals, which had escaped from captivity. If the last observed individual was the same as the first one, it had survived for at least 110 days. Currently, by law most goshawks held in captivity cannot be a subspecies breeding in Japan. If exotic subspecies escaping from captivity bred with Japanese subspecies, native subspecies will be at risk of genetic disturbance due to hybridization.
We monitored the breeding performance of Black-tailed Gulls Larus crassirostris on Kabushima Island, which has been connected to Honshu Island by a manmade isthmus since the 1940’s, from 2012 to 2020. The mean number of eggs per nest on 13–20 May between 2014 and 2020 (2.01‒2.16 egg/nest), except for 2019, was higher than that in 2012, 2013, and 2019 (1.57‒1.80 egg/nest). However, the number of chicks on 5–15 July per number of eggs on 13–20 May in 2014 and 2020 (0.01‒0.17 chick/egg) was lower than that in 2012 and 2013 (0.23‒0.29 chick/egg).
Monitoring Avian Productivity and Survivorship (MAPS) is a method developed in North America to monitor local avian fauna by constant-effort mist netting and banding during breeding seasons across years. Following the protocol of MAPS, we have been studying avian fauna in Fukushima, Japan since 2012. Here, we report the results obtained from 2018 to 2020. Also, results including adult abundance index, productivity index, and apparent adult survival rate from the entire study period (2012–2020) were analyzed. Adult abundance of the Japanese Bush Warbler Cettia diphone at a study site in Minami-Soma City were relatively stable. At a study site in Iitate Village however, adult abundance of this species fluctuated greatly. Adult abundance of the Oriental Reed Warbler Acrocephalus orientalis in Minami-Soma has been increasing steadily during the study years while that of the Oriental Greenfinch Chloris sinica has increased in the later years (2018–2020). Adult survival of the Oriental Reed Warbler from 2012–2013 to 2018–2019 in Minami-Soma was 0.15–0.40 (mean=0.26).