General

Where are all the Western Toads?

Thea Venckus from Nicasio sent in this week’s Ask the Naturalist question: Hi, I have lived on a ranch in Nicasio, for 13 years now. We used to have a multitude of western toads (Anaxyrus boreas) but I no longer see them. We still have abundant Pacific tree frogs, and bullfrogs in our deep pond. I was wondering what happened to all the toads?

Wildlife Ecotoxicology of Pesticides: Can We Track Effects to the Population Level and Beyond?

During the past 50 years, the human population has more than doubled and global Agricultural production has similarly risen. However, the productive arable area has increased by just 10%; thus the increased use of pesticides has been a consequence of the demands of human population growth, and its impact has reached global significance. Although we often know a pesticide´s mode of action in the target species, we still largely do not understand the full impact of unintended side effects on wildlife, particularly at higher levels of biological organization: populations,
communities, and ecosystems. In these times of regional and global species declines, we are challenged with the task of causally linking knowledge about the molecular actions of pesticides to their possible interference with biological processes, in order to develop reliable predictions about the consequences of pesticide use, and misuse, in a rapidly changing world.

Henk Tennekes urges Canada’s Pest Management Regulatory Agency to conduct a comprehensive review of the environmental impact of neonicotinoid insecticides

I understand that Canada’s Pest Management Regulatory Agency recently announced that it “has determined that current agricultural practices related to the use of neonicotinoid-treated corn and soybean seed are affecting the environment due to impacts on bees and other pollinators” (based on findings in Ontario and Quebec). They are applied as seed dressings on wheat and canola on the prairies, and that PMRA is providing an opportunity for public comment. I would like to urge PMRA to conduct a serious, more comprehensive review of the environmental impact of neonicotinoid insecticides. My reasoning is as follows. Insects are quietly but rapidly disappearing. The great American biologist, E O Wilson, said insects were world-rulers, because they play a central role in maintaining ecosystems and the whole web of life. The recent alarms in Europe and America about the fate of the honey bee – colonies have been crashing in increasing numbers – have started to open people's eyes to insects' importance in a more general way. But it is only the beginning of an understanding, and much more is needed if we are to take the action necessary to preserve our populations of insects and other invertebrates, the creatures without backbones which make up the majority of animal life, including snails, worms and spiders (spiders being arachnids, not insects).

Three leading Australian environmental scientists have called for a substantial change to the way the world responds to wildlife that is going extinct

In a paper provocatively entitled “Counting the books while the library burns”, the researchers produce evidence that many wildlife programs round the world are monitoring species to the point of extinction – often without taking the necessary action to save them. Professor David Lindenmayer and Dr Maxine Piggott of the ARC Centre of Excellence for Environmental Decisions (CEED) and the Australian National University, and Assoc. Professor Brendan Wintle of CEED and the University of Melbourne warn in the journal Frontiers of Ecology that some conservation programs are standing by and watching species die out. Their work, funded through Australia’s National Environmental Research program (NERP), highlights the growing challenge of saving almost 20,000 endangered animals, birds and reptiles from extinction – and proposes a new action plan. “Of the 63,837 species assessed worldwide using the International Union for Conservation of Nature (IUCN) Red List criteria, 865 are extinct or extinct in the wild and 19,817 are listed as critically endangered, endangered, or vulnerable to extinction,” the researchers say. “Since the start of the 21st century alone, at least 10 species of vertebrates are known to have gone extinct, although this is likely to be a substantial underestimate.”

Kröten und Fröschen in Berlin vom Aussterben bedroht

Sie knattern, pfeifen, quaken: Das Balzritual von Kröten und Fröschen ist eigentlich kaum zu überhören. Doch Forscher registrieren es in Berlin immer seltener: Viele Amphibienarten seien in ihrer Existenz bedroht, warnt der Biologe Rolf Schneider. "Die Entwicklung der vergangenen zehn Jahre ist schrecklich", sagt der Wissenschaftler der HU Berlin. Wie zuletzt eine Arbeit an seinem Institut ergab, ist etwa die streng geschützte Kreuzkröte im Norden Berlins ausgestorben. Wenig anders wird es der Wechselkröte ergehen, befürchtet Schneider. In Deutschland leben nach Angaben des Bundes für Umwelt und Naturschutz (BUND) 21 der rund 6000 weltweit bekannten Amphibienarten - rund die Hälfte davon gilt als bedroht. "Problematisch ist es für Amphibien vor allem dort, wo Landwirte unser Essen anbauen", sagt Artenschutzexperte Julian Heiermann vom Naturschutzbund (Nabu). Pestizide machen Insekten den Garaus, die auf dem Speiseplan der Kröten stehen. "Zudem reagiert auch die Haut der Amphibien auf Chemikalien sehr empfindlich." Überdüngung wiederum zerstört den natürlichen Lebensraum der Kröten: Nitrat lässt Tümpel umkippen. Es gerate vor allem dort ins Wasser, wo intensive Landwirtschaft und Gewässer dicht beieinander liegen, wie in der Uckermark, sagt Heiermann.

The last croak for Darwin's frog - Deadly amphibian disease chytridiomycosis has caused the extinction of Darwin's frogs

Deadly amphibian disease chytridiomycosis has caused the extinction of Darwin's frogs, believe scientists from the Zoological Society of London (ZSL) and Universidad Andrés Bello (UNAB), Chile. Although habitat disturbance is recognised as the main threat to the two existing species of Darwin's frogs (the northern Rhinoderma rufum endemic to Chile, and the southern Rhinoderma darwinii from Chile and Argentina), this cannot account for the plummeting population and disappearance from most of their habitat. Conservation scientists found evidence of amphibian chytridiomycosis causing mortality in wild Darwin's frogs and linked this with both the population decline of the southern Darwin's frog, including from undisturbed ecosystems and the presumable extinction of the Northern Darwin's frog. The findings are published today (20th Nov) in the journal PLOS ONE. Professor Andrew Cunningham, from ZSL's Institute of Zoology says: "Only a few examples of the "extinction by infection" phenomenon exist. Although not entirely conclusive, the possibility of chytridiomycosis being associated with the extinction of the northern Darwin's frog gains further support with this study."

The steep decline of insectivores in Ontario is telling us they're running out of insect food

Birds that eat flying insects are in a shocking and mysterious decline, says the co-editor of the new Atlas of Breeding Birds in Ontario. “It is an alarm bell,” Gregor Beck, a wildlife biologist and the book’s co-editor, said. The atlas, created after five years of research and employing 1.2 million individual bird records from Pelee Island to Hudson Bay, found most of the birds that eat flying insects declined 30 to 50 per cent in the last 20 years. The birds include some swallows, the common nighthawk (Chordeiles minor), the whip-poor-will (Caprimulgus vociferus) and the chimney swift (Chaetura pelagica). The decline was the biggest shock that came from the research, Beck said. We need to be very concerned, he said. Other insectivores are in steep decline as well. Reptile populations have declined drastically in Ontario over the past century. The Ontario Endangered Species Act, 2007 considers 18 of the province’s 24 reptile species (75%!) to be at risk. Fewer amphibian species are considered to be at risk, although amphibian populations are declining in parts of the province. Three species – timber rattlesnake, spring salamander and tiger salamander – have been extirpated.

Mesomycetozoean parasites threaten amphibian and freshwater fish populations

A new paper is calling for more attention to be paid to poorly-known micro-organisms capable of killing off amphibians and fishes. Chytridiomycosis, caused by the amphibian chytrid fungus, affects the skin of amphibians, is capable of killing rapidly, and is responsible for population declines and extinctions in amphibians globally. Not surprisingly, it is the most well-studied disease in amphibians. But it’s not the only fungal or ‘fungal-like’ disease out there. One particular group of fungal-like parasites called mesomycetozoeans (what is it with fungi and difficult to pronounce names!?) are very poorly-studied parasites capable of causing high mortality rates in fish and amphibian populations. Mesomycetozoeans are microscopic, but can cause visible lesions on skin, muscle or internal organs in amphibians and freshwater fishes, and these infections can kill. Although we don’t know much about them, several aspects of the biology of mesomycetozoeans are particularly worrying. They are highly virulent (deadly!) under certain conditions, aren’t at all fussy about which species they infect (even jumping from fish to frog, for example), and have a free-living infectious stage. Together, these characteristics make them possible candidates for causing the extinction of their host species, just like the better-known amphbian chytrid fungus.

Early-life exposure to the herbicide atrazine makes frogs more susceptible to death from chytrid fungal disease

Early-life exposure to the herbicide atrazine makes frogs more susceptible to death from chytrid (Batrachochytrium dendrobatidis), a fungal disease implicated in amphibian declines across the globe. The research, Early-life exposure to a herbicide has enduring effects on pathogen-induced mortality, published in the Proceedings of the Royal Society B and led by University of South Florida (USF) biologist Jason Rohr, Ph.D, provides critical information for scientists hoping to stem the global demise of amphibian populations. “Understanding how stressors cause enduring health effects is important because these stressors might then be avoided or mitigated during formative developmental stages to prevent lasting increases in disease susceptibility,” Dr. Rohr explains.

Zorgen om de biodiversiteit van Hoeksche Waards Landschap

'Natuurlijke berm geeft energie’ is de titel van het rapport, dat de werkgroep C-factor van Hoeksche Waards Landschap (HWL) heeft samengesteld vanuit de zorg dat steeds meer bloemrijk grasland verdwijnt. Het gevolg is niet alleen een minder mooi aanzien, maar het betekent vooral een verlies van biodiversiteit. Doelstelling van de werkgroep is een biodiversiteit gericht beheer van de groenblauwe dooradering en een bijdrage leveren aan de nuttige toepassing van koolstof die is vastgelegd in het plantenmateriaal. In de Hoeksche Waard wordt 224 hectare aan dijktaluds en bermen door HWL ecologisch beheerd. Het totaal aantal hectares zonder productie functie is meer dan duizend. Er is een enorme winst te behalen als het op biodiversiteit gerichte beheer fors wordt uitgebreid. Het rapport is op te vragen via milieu@hwl.nl en binnenkort af te halen in Klein Profijt (Oud-Beijerland) en het Nationaal landschap centrum (NLC) (Numansdorp).