Monarch butterflies drop ominously in Mexico

The largest single year drop of the main North American continent population, but they have been in a steep decline for about a decade. It is estimated that from 1997's estimated population, it is now down over 93%. As always, habitat loss, herbacides and pesticides, possibly weakened before wintering by them and OE parasites. Could/would be a lot worse if some organised efforts to save them had not been in place. But it was not enough with three nations all having to be on the same page doing so working together. They probably never will be either in time to save them. I don't have the exact numbers on the western race, but they too have been in decline since at least the late 60's/early 70's that I have personal field experience with. Groves that I studied along the CA coast myself continued to spiral down, some I visited are no longer used at all.

Adam, I am afraid you are too optimistic.
When humanity will be gone, there won't be a single flower or butterfly still alive...

Adam,
I think most understood I meant the western population, but thank you for correcting my mistype.

Really? Tell us more.

Clark,

I found this online :
www.sciencelearn.org.nz/Science-Stories/Butterflies/Monarch-butterflies

which includes
"Adaptations to life in New Zealand
Monarchs in New Zealand do not follow the same migration pattern as their northern relatives. They have adapted their migration behaviour to suit local conditions. When the air temperature drops to 12.8°C, monarchs flock together in overwintering sites. These sites tend to be in milder coastal locations where the temperature remains at least 10°C. Overwintering monarchs prefer sites that are sheltered from the wind, have trees with a rough bark surface on which to cling and have a nearby source of nectar. The butterflies are mostly inactive, but on warm days, they fly, bask in the sunlight and feed. When the temperatures warm up, butterflies move inland to reproduce.

Swarms form regularly to overwinter at places such as Tauranga Bay in Northland. The Monarch Butterfly New Zealand Trust (MBNZT) was initially formed to protect this site. Other overwintering sites include areas of Hawke’s Bay, Nelson and Christchurch. The MBNZT encourages citizen scientists to tag butterflies so we can learn more about the migration and overwintering habits of monarchs."


The following webpage:
australianmuseum.net.au/Wanderer-Butterfly

has this information on monarch migration in Australia
"Seasonality
In summer, Wanderers are found throughout their range along the east coast of Australia from Queensland to South Australia, and in south-west Western Australia. They have also been found in isolated parts of the Northern Territory. They are strong fliers and can cover long distances during their adult life, which is about a month to six weeks in summer. During this time they can move to unoccupied areas to find new plants on which to lay eggs. They take nectar from flowers to maintain their energy levels as they go.

As winter approaches, the butterflies leave the inland areas as temperatures drop and migrate towards the coast. For Wanderers near the coast north of the Richmond River in New South Wales, breeding can continue for most of the year with one generation following another. Further south, adults that develop in autumn do not breed immediately. They remain in a non-breeding state throughout winter, some of them staying in the same district for several months.

In cooler areas, these non-breeding adults may gather together and hang from the branches of trees in large clusters of thousands of butterflies. This is known as over-wintering. The same trees are used for this year after year. The clusters are at first made up mainly of males. The females arrive a week or so later. During the warmth of the day the butterflies fly around the trees, but with the afternoon drop in temperature they settle to reform clusters. Cluster sites are known in the Sydney Basin and Hunter Valley, as well in the Mt Lofty Ranges, near Adelaide.

The clusters appear in about April and remain until about August or September, when the butterflies disperse after mating. The females are the first to leave, moving off to lay the first eggs of the new season on fresh spring growth. Succeeding generations extend the range across the country until the full summer range of the species is again occupied."

Adam.