Monarchs Reared in Winter in California Are Not Large Enough to Be Migrants. Comment on James et al. First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California. Insects 2021, 12, 946

A recent study in this journal aimed to understand certain changes in the wintering behavior of monarch butterflies, specifically in the western subpopulation of North America [...]

Reply to Davis, A.K. Monarchs Reared in Winter in California Are Not Large Enough to Be Migrants. Comment on “James et al. First Population Study on Winter Breeding Monarch Butterflies, Danaus plexippus (Lepidoptera: Nymphalidae) in the Urban South Bay of San Francisco, California. Insects 2021, 12, 946”

This is a reply to the comment from Davis [...]

Migratory Behavior of an Eastern North Pacific Gray Whale From Baja California Sur to Chirikov Basin, Alaska

Eastern gray whales undertake annual migrations between summer feeding grounds in the Bering and Chukchi Seas and winter breeding and calving lagoons in the west coast of Baja California, Mexico. On February 12, 2017, three adult gray whales were sighted at San José del Cabo, Mexico, in which one individual, named “María,” was tagged using a satellite telemetry transmitter (PTT). The PTT stopped the signal on July 11, 2017. María traveled 11,387 km during 149 days from San José del Cabo to the Chirikov Basin. The migration route was aligned close to the coastline (<23 km) from February to April. After passing Kodiak Island in May, María started traveling far away from the coastline (>70 km) into the Bering Sea, including the Chirikov Basin. During March, April, and May, María traveled long distances at relatively high speeds, in contrast to the lower speed during February, early March, and the arrival time to the feeding areas in May, June, and July. The total distance traveled by María during its migration from Ojo de Liebre Lagoon to the Chirikov Basin was 8,863 km during 61.5 days with an average speed of 5.5 km h–1; this excludes the 14 days and 591 km that María spent feeding on the coast of Kodiak Island in late April. The information provided by this tagged whale documents a single whales’ migration, which is consistent with previous studies and constitutes the most complete northbound reported migration of an eastern gray whale.

Interchange and movements of humpback whales (Megaptera novaeangliae) between western North Pacific winter breeding grounds in northern Luzon, Philippines and Okinawa, Japan

Humpback whales wintering in the northern Philippines and Okinawa, Japan, belong to the western North Pacific subpopulation, now recognised as a distinct population segment. The numbers for this subpopulation are low hence it is being proposed to be listed as endangered. Although previous research revealed movements between breeding grounds, the relationship between these areas remain little understood. Recent survey efforts in the Philippines resulted in a total of 234 photo-identified individuals from 1999-2016 while Okinawa had 1,445 from 1991-2014. Within the seasons a total of 100 matches were found between the two breeding grounds including 38 males and 24 females while the rest were unknown. Within these matches, eight individuals were recorded moving within seasons, including two individuals moving across seasons multiple times. The two whales were both males, where one was recorded in both breeding grounds in three different seasons (2005, 2008 and 2012). The shortest duration of recorded sightings between grounds was one whale seen in the Philippines in late March 2012 and in Okinawa 13 days later. More females with calves were sighted in the Philippines than in Okinawa and this may indicate the Philippines as a preferred nursing ground.

Western North American Monarchs: Spiraling into Oblivion or Adapting to a Changing Environment?

Monarch butterflies in western North America typically migrate each fall from the Pacific Northwest to overwintering sites in California. Winter 2020/21 saw the lowest number of overwintering western monarch butterflies ever recorded, but was also marked by a winter-breeding population in the San Francisco bay area that appeared to be the largest ever seen. Recoveries of monarchs with wing tags from the Pacific Northwest suggested that many non-reproductive migrants in fall 2020 became reproductive in the San Francisco bay area and did not reach coastal overwintering sites. Mean daily maximum temperatures for San Francisco during fall and winter increased by ~1 °C during the past decade and were 2.5 °C above the 30 year mean during September-October 2020. Warm fall and winter temperatures along with the availability of non-native milkweeds likely caused the increase in winter breeding in winter 2020/21. The outcome of continued winter-breeding in the San Francisco bay area is uncertain. Whether it becomes a sink or source will be dependent on whether winter-breeding monarchs can re-enter their migratory state during spring. However, endemic levels of infection by the protozoan parasite, Ophryocystis elektroscirrha (OE), are often high in winter-breeding monarchs which can limit migration success. The eventual co-existence of winter-breeding and non-breeding monarch populations in northern and central California is probable, with an optimistic view suggesting that the adaptability of the monarch butterfly will allow it to persist in a changed environment.

Autumn–winter breeding by the Spotted Harrier Circus assimilis in southern Victoria

The breeding cycle of a pair of Spotted Harriers Circus assimilis was observed in southern Victoria, at 38°S, in autumn–winter 2017 for 42 hours over 22 days from incubation to the post-fledging period. From hatching on 10 June and fledging on 19 July, laying was inferred to have commenced on c. 8 May. Three chicks fledged from an initial brood of four; the nestling period was 38 days for the first-hatched chick. Rodents dominated a small sample of identified prey during a plague of House Mice Mus musculus. The male prey-delivery rate to the incubating female was 0.32 item/h, whereas during the nestling period the male brought 0.71 item/h and the female 0.11 item/h for a combined effective delivery rate of 0.64 item/h to nestlings. The combined parental feeding rate to new fledglings was 0.65 item/h. Parental behaviour is described. Juveniles were dependent for 6 weeks after fledging.