PL Migration

[Ray Hamblett]

Hi,

I havent written anything to this list before, but i found myself wondering about this now almost legendary Painted Lady migration.

Maybe someone can help, 

First is there a recommended text written about the butterfly migration phenomena ?.
Migration in general is kind of hard to get the mind around, how is it that thousands or millions of individuals all have the same 'idea' at the same time.

Where does the impulse come from?

Is there an external trigger, or is it built into evolution?

Is it a learned inheritance maybe, did a lot of species members perish until it was found that travelling vast distances was beneficial to the species. 

Are the distances constant or getting greater or smaller.

What will the butterflies do when they get to sea again after crossing the british mainland, do they ever reach the outer islands, if so why.

Just rambling thoughts

Ray 

have a good weekend all

:)

[Simon Davey]

Dear Ray

 

The main reasons, as I understand it for dramatic migrations of the sort we are now experiencing with Painted Ladies are.

 

1. That the population density where the insects hatched goes over a certain level. This causes the insects to disperse as in migratory locusts.

 

2. That the prevailing weather conditions are such as to carry insects that have been effected by an over crowding signal to move in a direction, in this case northwards. I did in fact one year, see a Painted Lady that had gone all the way to Iceland where there are no native butterflies of any kind.

 

3. There are a few insects, such as the Monarch Butterfly that have a built in need to migrate at certain times of the year. This does not appear to be such a regular phenomenon in the Old World.

 

The butterflies arriving in the UK will breed until weather conditions in the late autumn, or early winter become sufficiently adverse to make further breeding impossible, and the population will diminish to the normal levels that exist here. In the case of Clouded Yellows, which may well exhibit similar behaviour this year, conditions become so unfavourable that the population disappears altogether, though I have heard rumours of a very few surviving our winter. I guess global warming may help.

 

In the autumn, several American birds make it across the Atlantic carried by strong weather systems that push them off their usual migration routes. Although they cause great excitement amongst the birding world, they are mostly lost, and will never find their way back to their breeding grounds. Some bird groups, notably waders do appear to have a worldwide distribution ability, and probably do find their way home.

 

Just a few thoughts that hopefully will be welcome, and helpful.

 

Simon Davey

-----Original Message-----
From: adastra-bounces@... [mailto:adastra-bounces@...]On Behalf Of Ray Hamblett
Sent: 29 May 2009 12:58
To: sxbrc
Subject: [Adastra] PL Migration

Hi,

I havent written anything to this list before, but i found myself wondering about this now almost legendary Painted Lady migration.

Maybe someone can help, 

First is there a recommended text written about the butterfly migration phenomena ?.
Migration in general is kind of hard to get the mind around, how is it that thousands or millions of individuals all have the same 'idea' at the same time.

Where does the impulse come from?

Is there an external trigger, or is it built into evolution?

Is it a learned inheritance maybe, did a lot of species members perish until it was found that travelling vast distances was beneficial to the species. 

Are the distances constant or getting greater or smaller.

What will the butterflies do when they get to sea again after crossing the british mainland, do they ever reach the outer islands, if so why.

Just rambling thoughts

Ray 

have a good weekend all

:)

[Ray Hamblett]

thank you simon.

Your thoughts are welcome and have helped.

I wonder  is their any evidence of them using earth's magnetic fields ?

Any thoughts anyone...

Ray

:)

2009/5/29 Simon Davey <srdavey@...>

Dear Ray

 

The main reasons, as I understand it for dramatic migrations of the sort we are now experiencing with Painted Ladies are.

 

1. That the population density where the insects hatched goes over a certain level. This causes the insects to disperse as in migratory locusts.

 

2. That the prevailing weather conditions are such as to carry insects that have been effected by an over crowding signal to move in a direction, in this case northwards. I did in fact one year, see a Painted Lady that had gone all the way to Iceland where there are no native butterflies of any kind.

 

3. There are a few insects, such as the Monarch Butterfly that have a built in need to migrate at certain times of the year. This does not appear to be such a regular phenomenon in the Old World.

 

The butterflies arriving in the UK will breed until weather conditions in the late autumn, or early winter become sufficiently adverse to make further breeding impossible, and the population will diminish to the normal levels that exist here. In the case of Clouded Yellows, which may well exhibit similar behaviour this year, conditions become so unfavourable that the population disappears altogether, though I have heard rumours of a very few surviving our winter. I guess global warming may help.

 

In the autumn, several American birds make it across the Atlantic carried by strong weather systems that push them off their usual migration routes. Although they cause great excitement amongst the birding world, they are mostly lost, and will never find their way back to their breeding grounds. Some bird groups, notably waders do appear to have a worldwide distribution ability, and probably do find their way home.

 

Just a few thoughts that hopefully will be welcome, and helpful.

 

Simon Davey

-----Original Message-----
From: adastra-bounces@... [mailto:adastra-bounces@...]On Behalf Of Ray Hamblett
Sent: 29 May 2009 12:58
To: sxbrc
Subject: [Adastra] PL Migration

Hi,

I havent written anything to this list before, but i found myself wondering about this now almost legendary Painted Lady migration.

Maybe someone can help, 

First is there a recommended text written about the butterfly migration phenomena ?.
Migration in general is kind of hard to get the mind around, how is it that thousands or millions of individuals all have the same 'idea' at the same time.

Where does the impulse come from?

Is there an external trigger, or is it built into evolution?

Is it a learned inheritance maybe, did a lot of species members perish until it was found that travelling vast distances was beneficial to the species. 

Are the distances constant or getting greater or smaller.

What will the butterflies do when they get to sea again after crossing the british mainland, do they ever reach the outer islands, if so why.

Just rambling thoughts

Ray 

have a good weekend all

:)