Biologically significant residual persistence of brodifacoum in reptiles following invasive rodent eradication, Galapagos Islands, Ecuador

Rat eradication resulted in prolonged presence of the anticoagulant rodenticide brodifacoum in exposed lizards, likely significantly contributing to the deaths of secondarily exposed raptors up to at least 773 days after bait application

Invasive parasites habitat change and heavy rainfall reduce breeding success in Darwin's finches

Invasive alien parasites and pathogens are a growing threat to biodiversity worldwide, which can contribute to the extinction of endemic species. On the Galápagos Islands, the invasive parasitic fly Philornis downsi poses a major threat to the endemic avifauna. Here, we investigated the influence of this parasite on the breeding success of two Darwin's finch species, the warbler finch (Certhidea olivacea) and the sympatric small tree finch (Camarhynchus parvulus), on Santa Cruz Island in 2010 and 2012. While the population of the small tree finch appeared to be stable, the warbler finch has experienced a dramatic decline in population size on Santa Cruz Island since 1997. We aimed to identify whether warbler finches are particularly vulnerable during different stages of the breeding cycle. Contrary to our prediction, breeding success was lower in the small tree finch than in the warbler finch. In both species P. downsi had a strong negative impact on breeding success and our data suggest that heavy rain events also lowered the fledging success. On the one hand parents might be less efficient in compensating their chicks' energy loss due to parasitism as they might be less efficient in foraging on days of heavy rain. On the other hand, intense rainfalls might lead to increased humidity and more rapid cooling of the nests. In the case of the warbler finch we found that the control of invasive plant species with herbicides had a significant additive negative impact on the breeding success. It is very likely that the availability of insects (i.e. food abundance) is lower in such controlled areas, as herbicide usage led to the removal of the entire understory. Predation seems to be a minor factor in brood loss

Philornis downsi (Diptera: Muscidae), an avian nest parasite invasive to the Galápagos Islands, in Mainland Ecuador

Philornis downsi (Dodge and Aitken) is a bird-parasitic muscid fly native to mainland South America that recently invaded the Galápagos Islands where it is parasitizing Darwin's finches and other land birds. This parasite was previously known only from Argentina, Brazil, and Trinidad and Tobago. The first report of P. downsi from mainland Ecuador is provided, supporting the hypothesis that the invasion route of P. downsi from its native range to the Galápagos Islands includes mainland Ecuador. Four different morphologies of pupal exuviae, which belong to different fly species, were uncovered. Dipteran puparia were found in 20% of naturally occurring nests collected in 2013 and in 27% of nests in 2014 at the two sites in western Ecuador. P. downsi accounted for 74% and 40% of the puparia in 2013 and 2014, respectively. Two new bird host species for the genus Philornis were recorded: the streak-headed woodcreeper (Lepidocolaptes souleyetii) and the fasciated wren (Campylorhynchus fasciatus). The levels of nest parasitism found were much lower than levels reported for the Galápagos Islands. Finally, parasitism of P. downsi by a parasitoid in the genus Brachymeria (Hymenoptera, Chalcididae) is documented. Overall, 9% of fly puparia collected in 2013, and 19% of those collected in 2014, had parasitoid emergence holes.Fil: Bulgarella, Mariana. University of Minnesota; Estados UnidosFil: Quiroga, Martin Anibal. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Brito Vera, Gabriel A.. Universidad de Guayaquil; EcuadorFil: Dregni, Jonathan S.. University of Minnesota; Estados UnidosFil: Cunninghame, Francesca. Charles Darwin Foundation for the Galápagos Islands; EcuadorFil: Mosquera Muñoz, Denis A.. Universidad de Guayaquil; EcuadorFil: Monje, Lucas Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto de Ciencias Veterinarias del Litoral. Universidad Nacional del Litoral. Facultad de Ciencias Veterinarias. Instituto de Ciencias Veterinarias del Litoral; ArgentinaFil: Causton, Charlotte E.. Charles Darwin Foundation for the Galápagos Islands; EcuadorFil: Heimpel, George E.. University of Minnesota; Estados Unido

The comparative ecology of Stewart Island weka (Gallirallus australis scotti) on islands with and without seabirds

The spatial ecology of Stewart Island weka (Galliralluis australis scotti) was compared between a seabird island (Taukihepa/Big South Cape Island) and a predator-free non-seabird island (Ulva Island). Both islands were situated off Stewart Island in southern New Zealand. Differences in the spatial ecology of weka can be expected to occur between islands due to the recognised increases in productivity of seabird islands and the corresponding differences in ecology of animals high up the food chain, hence weka on the seabird island were expected to have smaller home ranges. Comparisons between weka home range, body size, social structure and 3rd order habitat selection were made between islands, after radio-tracking 11 and 10 weka on a seabird and non-seabird island respectively between January and May 2005. The results were contrary to those expected for a highly productive seabird island. This most likely occurred due to a reduction of male weka on the seabird island. The mean home range size of weka did not differ between the two islands (Taukihepa: 3.91 ± 0.83 ha, Ulva: 2.54 ± 0.50 ha) and was similar to weka home range sizes on other islands. There was no significant difference in the home range size between male (Taukihepa: 3.55 + 0.83 ha, Ulva: 2.84 ± 0.79 ha) and female (Taukihepa: 4.12 + 1.2 ha, Ulva: 2.09 ± 0.44 ha) weka which differed from past research. Male weka on Taukihepa had a greater amount of their home ranges overlapped by breeding partners than those on Ulva Island. There was a female-biased sex ratio on Taukihepa and a polygamous breeding strategy. All observed nests of polygamous weka failed. Conversely the sex ratio was even on Ulva Island, weka were monogamous and breeding success appeared to be high. In contrast to the hypothesis of resource-rich seabird islands resulting in an increase of body size for top predators, weka on seabird islands did not attain greater body weights than those on non-seabird islands. Habitat selection of weka on Taukihepa showed a strong preference for areas of low cover. On Ulva Island habitat selection was random with weka utilising mixed-podocarp forest and open coastal areas according to their availability. On Ulva Island coastal resources enabled weka living in the marine interface to have smaller home ranges than those living inland. This research stands as the only record of the home range and habitat use of Stewart Island weka. Due to the declines of weka populations throughout New Zealand, such information is important for their future management

Effect of herbicide use on the breeding success of warbler finches.

<p>Percentage of successful warbler finch nests in areas with no control measures by the National Park (2010: n = 14, 2012: n = 32) and in areas where the National Park recently sprayed herbicides to control the invasive <i>Rubus niveus</i> (2010: n = 12, 2012: n = 42). Numbers above bars indicate total numbers of cases.</p

Population trends of warbler finches and small tree finches.

<p>Mean (± SD) number of singing warbler finch males and small tree finch males per point count in the <i>Scalesia</i> zone on Santa Cruz, Galápagos, for the years 1997, 1998, 2008, 2010 (data from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0107518#pone.0107518-Dvorak1" target="_blank">[27]</a>), 2004 and 2005 (Dvorak et al. unpublished data) and 2012.</p

Breeding success and types of nesting failure.

<p>Proportional nesting outcome for the breeding season 2010 (A) and 2012 (B) of warbler finch nests and small tree finch nests of the <i>Scalesia</i> zone population on Santa Cruz, Galápagos. Numbers above bars indicate total numbers of cases.</p

Age of chicks at brood loss.

<p>Percentage of nests with total brood loss depending on the chicks' age. Warbler finch (n = 21), small tree finch (n = 31). Total brood loss included the following types of nesting failures: dead chicks in the nest, empty nest and predated nests. Numbers above bars indicate total numbers of cases.</p

<i>Philornis downsi</i> intensity in warbler finch and small tree finch nests.

<p>Mean (± SD) number of <i>P. downsi</i> specimens (larvae, pupae and puparia) per nest of the breeding season 2012 of warbler finches and small tree finches for all nests with chicks (warbler finch n = 44, small tree finch n = 38), nests with chicks of six days and younger (warbler finch n = 11, small tree finch n = 20) and nests with chicks of seven days and older (warbler finch n = 33, small tree finch n = 18).</p