A problem in paradise: The vanishing Picobar Tree Frog

Geoff HydeNCBSYETI 2009Bangalore

Species Unique to Picobar346 plants209 insects37 birds14 mammals11 reptiles and amphibians

Picobar Tree Frog

Dyscophus picobari

DiurnalInsectivorousMid-altitudesPopulation declining

How can the population decline of the Picobar Tree Frog be halted?

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 ?

27oC

Preparation for exposure to insects

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

27oC

What if frogs can't choose Lady Beetles?

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

• Very unlikely due to Rat Snakes

Is decline of Picobar Tree Frogs due to increased Rat Snake predation or

decreased availability of Lady Beetles?

• Results support Lady Beetle hypothesis- need support from field studies - preliminary data is suggestive

• Breed fungal-resistant Lady Beetles

• Captive breeding program for tree frogs

Suggestions for management of population decline