The Conservation Ecology of Rana temporaria and Bufo bufo in Leicestershire

Past and present surveys of Leicestershire farming areas showed that amphibian habitat has been reduced as land use diversities, scrubs, woodland and thorn hedge cover have decreased within the previous decade. Breeding pond surveys revealed Rana temporaria to breed in areas with no rough vegetation in field ponds as small as 35 m3, but Bufo bufo only in ponds over 100 m3, in areas where scrub vegetation cover exceeded 2.5% of the total area. The densities of all ponds and R. temporaria and B. bufo breeding ponds have been reduced at the rates of 2.6, 1.3 and 0.7 per km per 10 years respectively. An anuran habitat suitability index was devised. Drift fence and pitfall trap captures indicated the origins of frog and toad pre-breeding migrations and subsequent terrestrial habitat to comprise scrub and woodland, water courses to be the main migration routes. Ingestion of radio transmitters proved not to impair the appetites or be injurious to frogs and toads. Transmitter implanted toads inhabited rough vegetation by day, foraging over ploughed land by night. Tadpole field sampling proved an inadequate breeding site survey technique for both species but revealed frog larvae to be widely dispersed mainly just below the pond surface water. Toad tadpoles localised high density aggregations throughout the water column showing a highly clumped distribution and in experiments were less heavily predated or prone to cannibalism than frog larvae. Translocated frog tadpoles survived in more non-breeding pods than those of the toad. Trough, traps efficient for catching newly metamorphosed toads but not frogs, indicated mass emergence and dispersal towards areas of thick cover in the former. In laboratory experiments, toad metamorphic success was less density dependent than that of the frogs. Skeletochronology of toad phalanges revealed age to be correlated with size, but bone resorption to distort section dimensions. Toad but not frog size and fecundity varied between sites. Dissections of female toads prevented from spawning showed mature oocytes to be resorbed, indicating the potential for biennial breeding. Stomach content analysis showed pre-breeding toads, but not frogs, to feed, beetles comprising the most abundant prey items. The most abundant and diverse invertebrates samples came from beneath scrub vegetation surrounding an arable field, the least diverse from under the crop itself. Anuran conservation recommendations are provided.

Name dc:type.qualificationname

PhD

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

De Montfort University

Year dc:date.issued

1986

Author dc:creator

• Swan, Mary Jane Sinclair

Licence

• https://dora.dmu.ac.uk/bitstreams/d7e6298f-53aa-4ec2-b2da-ca6eb466bac7/download