Do Some Fall Migrants from the Pacific Northwest Augment Winter Breeding Populations of Monarch Butterflies in Southern California?

2018 ◽  
Vol 72 (3) ◽  
pp. 244-246
Author(s):  
David G. James
2021 ◽  
Vol 8 (1) ◽  
pp. 19-26
Author(s):  
David G James

Abstract 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.


The Auk ◽  
1978 ◽  
Vol 95 (3) ◽  
pp. 441-458 ◽  
Author(s):  
Wayne Hoffman ◽  
John A. Wiens ◽  
J. Michael Scott

Abstract Interbreeding between Glaucous-winged Gulls (Larus glaucescens) and Western Gulls (L. occidentalis) occurs extensively within a 180-km zone along the Washington coast, producing a high frequency of intermediate morphs in breeding populations. We conducted intensive studies on Destruction Island, Washington, in the midst of the zone of hybridization. There over half of the breeding birds were phenotypically intergrades between pure Glaucous-winged and Western gulls in characters of iris and eye-ring coloration, mantle shade, and wing tip pattern. Mating patterns of Destruction Island gulls were assortative, individuals pairing with mates similar to themselves. Pairs composed of pure Glaucous-winged or Western gulls hatched significantly fewer eggs than pairs containing at least one hybrid individual. The greater apparent reproductive success of the intergrades would seem to be countered by the assortative mating patterns, possibly providing conditions sufficient to maintain an equilibrium system containing both pure types as well as intergrades. These conditions are explored in a simulation model that considered immigration, density-dependent fecundity, pairing and reproduction, and mortality. A stable colony of mixed composition may be maintained by a regular but small influx of pure types into the colony.


2018 ◽  
Vol 72 (2) ◽  
pp. 127-144 ◽  
Author(s):  
David G. James ◽  
Tanya S. James ◽  
Lorraine Seymour ◽  
Linda Kappen ◽  
Tamara Russell ◽  
...  

1996 ◽  
Vol 14 (6) ◽  
pp. 683-708 ◽  
Author(s):  
James D Proctor ◽  
Stephanie Pincetl

Recent efforts to protect biodiversity in the United States often reproduce the literal and figurative divisions of space that have originally endangered target species. Nature as redefined by these efforts is as much a social construction as it is some biophysical entity under siege by humans, We focus on the categorical and spatial distinctions between landscapes prioritized for protection and landscapes given less priority or ignored altogether. These distinctions, we wish to demonstrate, reflect pragmatic considerations of habitat quality and political expediency, but they also are enmeshed in dualist nature–culture ideologies that serve to legitimate and ultimately to reproduce the different practices that occur on these landscapes. We focus on protection of spotted owl habitat, one of the most important cases of biodiversity conservation in the United States since the passage of the Endangered Species Act. We consider recent spotted owl protection efforts in the Pacific Northwest and southern California. In the Pacific Northwest, spotted owl protection plans on public forests have been cited as justification for casing habitat protection on private lands, in spite of the major historical biodiversity role of these forestlands. In California, spotted owl policy deliberations for the urbanized forests of southern California have lagged far behind those in the Sierra Nevada, even though owl populations have declined faster in southern California than anywhere else in the state. These cases are indicative of a nature epistemologically understood and ontologically constructed as separate from culture, of what Latour would call an act of purification set up against the undeniably hybrid character of nature–cultures in late modernity. It is precisely this recognition of nature–culture intertwining, however, that will prove central to the creation of sustaining habitats for nonhuman life.


Insects ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 161
Author(s):  
David G. James ◽  
Linda Kappen

The fall migration of monarch butterflies, Danaus plexippus (L.), in the Pacific Northwest was studied during 2017–2019 by tagging 14,040 captive-reared and 450 wild monarchs. One hundred and twenty-two captive-reared monarchs (0.87%) were recovered at distances averaging 899.9 ± 98.6 km for Washington-released and 630.5 ± 19.9 km for Oregon-released monarchs. The greatest straight-line release to recovery distance was 1392.1 km. A mean travel rate of 20.7 ± 2.2 km/day and maximum travel of 46.1 km/day were recorded. Recovery rates were greater for Oregon-released monarchs (0.92%) than Washington-released (0.34%) or Idaho-released monarchs (0.30%). Most monarchs (106/122) were recovered SSW-S-SSE in California, with 82 at 18 coastal overwintering sites. Two migrants from Oregon were recovered just weeks after release ovipositing in Santa Barbara and Palo Alto, CA. Two migrants released in central Washington recovered up to 360.0 km to the SE, and recoveries from Idaho releases to the S and SE suggests that some Pacific Northwest migrants fly to an alternative overwintering destination. Monarchs released in southern Oregon into smoky, poor quality air appeared to be as successful at reaching overwintering sites and apparently lived just as long as monarchs released into non-smoky, good quality air. Migration and lifespan for monarchs infected with the protozoan parasite, Ophryocystis elektroscirrha (McLaughlin and Myers), appeared to be similar to the migration and survival of uninfected monarchs, although data are limited. Our data improve our understanding of western monarch migration, serving as a basis for further studies and providing information for conservation planning.


2019 ◽  
Vol 39 (4) ◽  
pp. 452
Author(s):  
Margaret H. Massie ◽  
Todd M. Wilson ◽  
Anita T. Morzillo ◽  
Emilie B. Henderson

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