FORS2355 Vertebrate Natural History
Lecture 15 Perspectives on Amphibian Conservation
October 13, 2021
Lab Next Week:
1. Bring bird field guide 2. Watch 2nd bird video 3. Meet in Miller 218
Lecture Exam: November 1st
Amphibian Declines
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One third of amphibian species are declining fi Proportionally, more amphibians are threatened than birds or mammals fi 20% of species are data deficient o Insufficient data to determine their status o Vulnerable to declines
Declining Amphibian Populations: The Problem of Separating Human Impacts from Natural Fluctuations
fi. Savannah River Site in Sc fi Monitored Rainbow Bay every day since 1978, using drift fence around wetlands -- ephemeral that dries each yearft each side of the fence there are pit fall trap. Check the pit fall traps. Longest amphibian data set that we have. fi Counted, sexed, marked every individual entering/leaving pond fi Shortfiterm status fi Walled off site to give a buffer between the wetland lab and the general public. fi In 19ffiOs sets up ecology lab -- the effects of nuclear radiation on amphibians
Fluctuations of substantial magnitude
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1000s metamorphose one year, few/none in other years fi Drought was responsible for recruitment failures fi Variation in the number of females in the wetland each year -- wet year encourages more females to come. Dry years do not attract females to the wetland.
Breeding Adult Population Size
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Positively correlated with hydroperiod fi May breed only in wet years fi 12,000 metamorphose in one year, few/none in other years fi Natural fluctuations within the amphibian populations fi Small term snapshot of these years -- conclusion that they are decliningft having longfiterm data sets, they bounce back pretty rapidly. Can model survivorship with this type of data.
Population dynamics controlled by factors across both life stages.
Small, isolated Wetlands
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E.g., Carolina Bays, Vernal Pools fi Filled via rainfall or snowmelt fi Usually dry seasonally, but can be semifipermanent Lack fish predators = optimal breeding habitats Most numerous on landscape/most abundant Ideal breeding habitats for amphibians - Ties to metapopulations
Use of Multiple Habitats
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Amphibians use distinctly different habitats o Different stages of life cycle o Different times of year fi Populations vulnerable to habitat degradation in one habitat o Regardless of if another habitat remains intact fi Amphibians -- spend only few days/weeks at breeding sites fi Understand how terrestrial habitats differ from one another fi Emigrate to terrestrial habitats o Forage Overwinter
Buffer Zones Around Wetlands
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Terrestrial buffers/riparian strips Sites of physical or chemical filtration processes -> protects water resources o 30fiffi0 m wide fi Important for conservation and management of semiaquatic species fi Function of buffer is to protect water quality in whatever wetland habitat through filtration for runoff. It is insufficient due to not being large enough. Need to maintain the integrity of the core habitat so it acts like a filter -- protects habitat from debris. Mean minimum and mean maximum -- how far the animals move from the wetland's edge fi So