Richard A. Griffiths

Blue tits are ultraviolet tits

The blue tit (Parus caeruleus) has been classified as sexually monochromatic. This classification is based on human colour perception yet, unlike humans, most birds have four spectrally distinct classes of cone and are visually sensitive to wavelengths in the near–ultraviolet (300 to 400 nm). Reflectance spectrophotometry reveals that blue tit plumage shows considerable reflection of UV light. For example, the blue crest shows peak reflectance at wavelengths around 352 nm. Furthermore, the blue tit is sexually dichromatic for multiple regions of plumage, including the crest. Choice trials performed in the laboratory indicate that females prefer males with the brightest crests. This study has implications for both intra– and interspecific studies of sexual selection, as well as future classification of dichromatism, which should not ignore the possibility of variation in reflectance in the UV.

Captive Breeding, Reintroduction, and the Conservation of Amphibians

The global amphibian crisis has resulted in renewed interest in captive breeding as a conservation tool for amphibians. Although captive breeding and reintroduction are controversial management actions, amphibians possess a number of attributes that make them potentially good models for such programs. We reviewed the extent and effectiveness of captive breeding and reintroduction programs for amphibians through an analysis of data from the Global Amphibian Assessment and other sources. Most captive breeding and reintroduction programs for amphibians have focused on threatened species from industrialized countries with relatively low amphibian diversity. Out of 110 species in such programs, 52 were in programs with no plans for reintroduction that had conservation research or conservation education as their main purpose. A further 39 species were in programs that entailed captive breeding and reintroduction or combined captive breeding with relocations of wild animals. Nineteen species were in programs with relocations of wild animals only. Eighteen out of 58 reintroduced species have subsequently bred successfully in the wild, and 13 of these species have established self-sustaining populations. As with threatened amphibians generally, amphibians in captive breeding or reintroduction programs face multiple threats, with habitat loss being the most important. Nevertheless, only 18 out of 58 reintroduced species faced threats that are all potentially reversible. When selecting species for captive programs, dilemmas may emerge between choosing species that have a good chance of surviving after reintroduction because their threats are reversible and those that are doomed to extinction in the wild as a result of irreversible threats. Captive breeding and reintroduction programs for amphibians require long-term commitments to ensure success, and different management strategies may be needed for species earmarked for reintroduction and species used for conservation research and education.

Invasive pathogens threaten species recovery programs

Summary Captive breeding and re-introduction is integral to the recovery of many threatened species [1], but such practices carry an associated risk of introducing exotic and potentially unknown pathogens into naive settings. Amphibians are facing a mass extinction crisis and an emerging pathogen, Batrachochytrium dendrobatidis , described only in 1998, is now recognised as a principal driver of these declines [2]. Debate rages about the role of invasion [2,3] versus climate change [4] in determining the distribution of B. dendrobatidis and chytridiomycosis. The severity of the threat from anthropogenic spread is recognized by the recent decision to list chytridiomycosis as a notifiable disease by the OIE (World Organisation for Animal Health) [5]. Case-studies documenting anthropogenic spread are rare, however. Here, we report that native island populations of the IUCN red-listed Mallorcan Midwife Toad Alytes muletensis are infected by B. dendrobatidis and suffering from chytridiomycosis. We trace the source of this infection by screening archived mortalities from a captive-breeding facility that had been used for re-introduction of the species to its native habitat. Our study provides the first strong evidence that the anthropogenic movement of amphibians is spreading B. dendrobatidis ; it also provides a salutatory lesson of the need to ensure that breeding-programs are not hot-beds for cross-specific disease transmission, and that species are free of infectious agents prior to re-introduction.

Low gene flow but high genetic diversity in the threatened Mallorcan midwife toad Alytes muletensis

We investigated fine‐scale genetic structuring in the rare and vulnerable Mallorcan midwife toad Alytes muletensis using eight polymorphic microsatellite markers. The current range of this amphibian is restricted to some 19 sites of which six are derived from reintroductions, all located in the mountain ranges of Mallorca. We sampled tadpoles from 14 pools covering 10 natural sites and two reintroduction sites for microsatellite DNA analyses. Relatively high levels of genetic variation were found in most pools (HE = 0.38–0.71, allelic richness = 2.6–6.2). Only at one pool has the population recently gone through a bottleneck. Dispersal between pools in different torrents does not occur whereas downstream dispersal between pools within the same torrent does happen at low frequencies. This occasional exchange of individuals does not lead to neighbouring pools in the same torrent being panmictic. This can be concluded because all FST values (0.12–0.53) differ significantly from zero and structure analyses identified neighbouring pools as separate populations. Furthermore, assignment and migration tests showed little exchange between neighbouring pools. If upstream locations or complete torrents go extinct, they are unlikely to be recolonized naturally. For conservation purposes, reintroductions of tadpoles to sites where local extinctions have occurred may therefore be advisable.

Life history traits and food supplementation affect productivity in a translocated population of the endangered Hihi (Stitchbird, Notiomystis cincta)

We studied the effect of food supplementation, female age and clutch order on productivity in a translocated species. Food supplementation increased clutch size from 3.9 to 4.4 (average) eggs per nesting attempt, and more than doubled fledging and recruitment success. Supplemented females started a second clutch 9 days sooner after fledging first clutch chicks than unfed females. During second clutches, supplemented females incubated the eggs for a shorter period of time (15.2 days vs. 16.8). Older females laid larger clutches (4.6 vs. 3.7 eggs) than yearlings and incubated second clutch eggs for a shorter period (15.4 vs. 16.6 days). Females laid more eggs in first clutches (4.2 vs. 3.8 eggs), and those eggs took approximately 30% longer to lay than eggs in second clutches. The successful maintenance of hihi populations on the available islands may be dependent on the permanent provision of supplemental food at nest sites.

Behavioural responses of Mallorcan midwife toad tadpoles to natural and unnatural snake predators

The activity levels of Mallorcan midwife toad tadpoles, Alytes muletensis, were compared in two natural torrent pools which differed in their use by predatory viperine snakes, Natrix maura. Activity levels were lower in a pool regularly used by snakes than they were in a snake-free pool, but were reduced in both pools when snakes were experimentally introduced in nylon bags. In the presence of snakes, however, activity was more suppressed in the pool that was usually snake-free. Corresponding reductions in activity were also observed when tadpoles were treated with chemical cues from Mallorcan N. maura in a gravitational flow-through system. However, tadpoles failed to respond to chemical cues from other species of amphibian-eating snakes, or even to those from N. maura collected from a different population in mainland Spain. As none of the snakes used had previously eaten midwife toads, the responses cannot be related to previous diet, and seem to be specific to those N. maura from the island of Mallorca. As viperine snakes were probably introduced to Mallorca about 2000 years ago, the evolution of anti-predator behaviour in midwife toad tadpoles must have occurred relatively recently. Copyright 1998 The Association for the Study of Animal Behaviour.

Induced defences in an endangered amphibian in response to an introduced snake predator

Introduced species have contributed significantly to the extinction of endemic species on islands. They also create new selection pressures on their prey that may result in modified life history strategies. Introduced viperine snakes (Natrix maura) have been implicated in the decline of the endemic midwife toad of Mallorca (Alytes muletensis). A comparison of A. muletensis tadpoles in natural pools with and without snakes showed that those populations subject to snake predation possessed longer tails with narrower tail fins but deeper tail muscles. Field and laboratory experiments showed that these changes in tail morphology could be induced by chemical and tactile cues from snakes. Populations of tadpoles that were subject to snake predation also displayed clear bimodal size-frequency distributions, with intermediate-sized tadpoles missing from the pools completely. Tadpoles in pools frequented by snakes developed faster in relation to their body size than those in pools without snakes. Variation in morphology between toad populations may therefore be caused by a combination of size-selective predation and tadpole plasticity. The results of this study indicate that the introduction of alien species can result in selection for induced defences, which may facilitate coexistence between predator and prey under certain conditions.

Introduced Alien or Persecuted Native? Resolving the Origin of the Viperine Snake (Natrix Maura) on Mallorca

The viperine snake (Natrix maura) is an important agent of decline of the threatened midwife toad (Alytes muletensis) of Mallorca. However, there is a paucity of biological data to support the notion that the viperine snake is an introduced species to the island. Here we compare mitochondrial cytochrome b gene sequences and genomic ISSR-PCR fingerprints from Mallorcan and mainland European viperine snakes. Identical or nearly identical haplotypes and very similar ISSR-PCR profiles provide strong evidence that N. maura arrived only recently to Mallorca. There is no indication of a recent natural colonization of the island by transmarine dispersal. The data therefore support historical information that N. maura was introduced to Mallorca by human agency comparatively recently, and that management measures to reduce the impact of the snake on toad populations are justified.

Translocation of slow-worms (Anguis fragilis) as a mitigation strategy: a case study from south-east England

Abstract Translocation is often used as mitigation in cases where sites containing protected species are threatened by development. However, the conservation value of such exercises is unproven for many species. This paper describes a case study in which translocation was used as a mitigation measure for the slow-worm (Anguis fragilis) a cryptic legless lizard. At a site scheduled for development, the removal of 103 lizards over a three-month period resulted in no significant depletion of the population. At the receptor site, which had no previous slow-worm population, recaptures of translocated slow-worms declined during 2 years of subsequent monitoring; recaptured lizards were in poorer condition than those in a nearby natural population; and there was little evidence of successful reproduction. As the exercise may have prevented the inadvertent killing of a number of slow-worms, it may have been successful in terms of meeting the statutory obligations for this species. As an exercise in conserving the population in the long-term, however, the value of the translocation was questionable.

Susceptibility of frog (Rana temporaria) and toad (Bufo bufo) eggs to invasion by Saprolegnia

Infections of amphibian eggs sometimes cause catastrophic losses of reproductive effort, but susceptibility to infection in different species is poorly understood. Using laboratory trials we showed that direct hyphal invasion of adjacent eggs by Saprolegnia caused a higher incidence of infection than invasion by zoospores. Moreover, we observed that dead eggs were much more readily colonized than live eggs when challenged with zoospores from two strains of Saprolegnia . The two strains were equally effective in causing infections of Rana temporaria eggs, but differed in their ability to infect eggs of Bufo bufo . In live R. temporaria eggs, early stages (pre-tailbud) were more frequently infected by hyphal invasion than later stages by the same strains, suggesting that susceptibility to infection decreases as development proceeds.