4155. Rapid decline in the number of butterflies and bees in Yio Chu Kang Crescent forest after Covid-19

25 Nov 2022:

From my observation during visits over the past 6 years, from 2016 - 2022, there are fewer species and numbers today.

Reasons:

1. Habitat degradation
1.1  Fewer flowers throughout their range.
      A large part of the forest path is dominated by ferns 

1.2  Frequent cutting and pruning of plants at the fringe of the forest

1.3  Frequent thermal fogging to kill mosquitoes

1.4  Construction of North South Corridors 

1.5  Climate change. Getting hotter in the past 2 years.  Butterflies don't lay eggs when it is too hot.

For example, monarchs in the U.S. Scientific American (scientificamerican.com) Mar 2022 - The Great Monarch Odyssey, pg 80, Scientific American, March 2022. 

Eastern monarch numbers have dropped 80% in the past 20 years because of habitat degradation. In Spring, every year, the butterflies leave their winter clusters near Mexcico City and head for northern latitudes to Canada to avoid the Summer heat of the south.   

 

In March, the monarchs that wintered in Mexico move north. In northern Mexico and the south U.S., they lay the eggs that will be the first generation of the next life cycle. 

Second generation in late May and early June are born. The South wll be too hot for monarchs, so those born there move north.

Third and fourth Generations emerge in late summer in the norther part of the monarch range in Canada. They will trek south again, starting in September. 

24 Nov 2022. At 9 am, I saw only two Chocolate Pansy butterflies in the Yio Chu Kang Crescent forest path plants. Used to see more than 10 during COVID-19 period of late 2020 - 2021. One or two yellow ones. That's all. Even dragonflies have declined in numbers. Saw two or three. Thermal fogging again in Seletar Bus Depot today (photo). Also done in this forest path. Plant cutting too. Tree pruning severely. Very few wild flowers. Even Bidens pilosa is few and small. Bees have had disappeared but small numbers are seen now.  No flowers - no butterflies. 
 
 

In September, they trek south from Canada again.

What is being done:
1. Rewilding

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Companion to Wildlife Gardening. Chris Baines

In the last century, bees have suffered the extinction of 2 species and a major decline in population.
Causes include:
 
1. Climate change
2. Intensive farming practice

3. Use of pesticides
4. Loss of habitat (loss of wildflower meadows)