Butterfly extirpations, discoveries and rediscoveries in Singapore over 28 years

Digital Gems > Biodiversity Library of Southeast Asia

Language

English

Creator

Jain, A
Khoon, K. S.
Gan, C. W.
Webb, E. L.

Source Title

The Raffles Bulletin of Zoology

Publication date

2018/04/19

Publisher

Dept. of Zoology, National University of Singapore, Singapore

Page

217–257

Content Type

Journal Article

Object Type

Text

Terms of Use

Open Access

Access Status

Open

Repository

NUS Libraries

Start File Page

217

End File Page

257

Volume

66

Issue

2

Call Number

QL319 NMB

Subject

Butterflies -- Singapore -- Classification
Butterflies -- Singapore -- Identification
Extinction (Biology) -- Singapore

Keyword

extinction
fragmentation
habitat degradation
Lepidoptera
Southeast Asia
urban ecology
checklist of species
new species

Abstract

Habitat loss and urbanisation in the tropics have been recognised as major drivers of species extinctions.
Concurrently, novel habitats such as urban parks have been shown to be important as habitats and stepping stones
in urban ecosystems around the world. However, few studies have assessed long-term patterns of species extinctions
and discoveries in response to these drivers in the tropics. We know little about long-term persistence and utility
of novel habitats in tropical urban ecosystems. In this study, we produced an updated and exhaustive butterfly
checklist of species recorded from Singapore till December 2017 to investigate trends in butterfly extirpations (local
extinctions), discoveries (new country records) and rediscoveries and how these relate to land use change in 28
years (1990–2017) in Singapore. Up to 144 butterfly species were identified to be extirpated in Singapore by 1990.
From 1990–2017, an additional nine butterfly extirpations have potentially occurred, which suggests a maximum
of 153 butterfly extirpations to date. The rate of extirpations between 1990 to 2017 (< 0.33 extirpations per year)
was much lower than the rate of extirpations between 1926 to 1989 (> 1.52 extirpations per year). The majority of
potentially extirpated butterflies between 1990 to 2017 were species restricted to mature forests. Over this period,
51 new species were discovered, while 65 species were rediscovered, which collectively represent 24% of the total
and 35% of the extant butterfly fauna of Singapore. Interestingly, 33% of discovered species were only observed
in degraded secondary forests or urban parks in Singapore, the former maturing with age and the latter having
increased in area during the same time period. We hypothesise that the current slowdown in butterfly extirpations
may be representative of habitat recovery and/or improved habitat connectivity, lower undetected extirpations,
and/or lengthening of extinction debts. A slowdown in extirpations and an increased utilisation of novel habitats
by discovered species present a window of conservation opportunity to restore native habitats and increase habitat
connectivity among existing patches of managed vegetation.

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