Transcript The science of science writing

A problem in paradise:
The vanishing Picobar Tree Frog
Geoff Hyde
NCBS
YETI 2009
Bangalore
Species Unique to Picobar
346 plants
209 insects
37 birds
14 mammals
11 reptiles and amphibians
How can the population decline of
the Picobar Tree Frog be halted?
Diurnal
Insectivorous
Mid-altitudes
Population declining
Picobar Tree Frog
Dyscophus picobari
Possible players in the population decline
of the Picobar Tree Frog
Rat Snake
(Ptyas mucosa)
Introduced 1999
Picobar Lady Beetle
(Harmonia picobari)
Threatened by fungi
Is population decline due to
increased predation or decreased prey?
If increased predation…..
… we should see snakes eating frogs
Objective 1: Do starved captive rat snakes
eat Picobar Tree Frogs?
Preparation for exposure to frogs
27oC + 36oC
Replication : 20 snakes
Snakes offered two species of frogs
Snakes ate the brown frogs
Tree frogs uneaten after one week
What if snakes do not have a choice?
27oC
Tree frogs only, offered for one week
Snakes sometimes attacked tree frogs...
...but quickly spat them out.
After one week, no frogs eaten
Objective 1: Do starved captive rat snakes
eat Picobar Tree Frogs?
No
If decreased prey, frogs should strongly
prefer Lady Beetles
Objective 2: Do starved, captive
Picobar Tree Frogs
strongly prefer
Picobar Lady Beetles ?
Preparation for exposure to insects
27oC
Replication : 20 frogs
Frogs offered five species of insects
Frogs targeted the Lady Beetles
5% Lady Beetles, 75% Brown Beetles,
100% of other species remain after a week
What if frogs can't choose Lady Beetles?
27oC
Replication : 20 frogs
Frogs offered 4 species (no Lady Beetles)
45% of Brown Beetles, 100% of other
species, remain after a week
Objective 2: Do starved, captive Picobar
Tree Frogs strongly prefer Picobar Lady
Beetles ?
Yes
Is decline of Picobar Tree Frogs due to
increased Rat Snake predation or
decreased availability of Lady Beetles?
• Very unlikely due to Rat Snakes
• Results support Lady Beetle
hypothesis
- need support from field studies
- preliminary data is suggestive
Suggestions for management of
population decline
• Breed fungal-resistant Lady Beetles
• Captive breeding program for tree frogs