LONGEVITY OF WOODHOUSE\u27S TOAD IN COLORADO

Little is known about the longevity of amphibians in nature. Records from captive specimens have demonstrated life spans of 10 to 20 yr for a number of anuran species, including 36 yr for Bufo bufo (Duellman WE, Trueb L. 1986. Biology of Amphibians. New York: McGraw-Hill. 670 p). Here, we report on a male Woodhouse\u27s toad (Bufo woodhousii) which appeared in 1978, and has apparently remained since, in a basement window well of a brick home in an unincorporated western suburb of Denver, Colorado (T3S, R69W, 530). In the intervening years no other toads have been observed in any of the other window wells around the house and no distinctive differences in size and appearance of this toad have occurred, which makes it unlikely that multiple animals over time could have been assumed to be a single individual. This individual has now been observed continuously during the warmer months for 19 yr. Although we cannot know its age when it first dropped into the window well, it is likely that this individual exceeds 20 yr of age. The site in which this toad trapped itself is well protected or removed from most potential predator species and offers reliable food sources (insects, spiders, earthworms), factors which undoubtedly provide optimal circumstances for maximal longevity. The window well structure is in a small garden along the east face of the home. A 1.5 m wooden fence to the south protects it from the sun, while a nearby faucet provides moisture from early spring through mid-fall

Common Ravens Conditioned to a Nutritious Seasonal Aquatic Food Source in Rocky Mountain National Park

Common Ravens (Corvus corax) are among the most intelligent of birds with extraordinary problem-solving capabilities (Heinrich 1995, Heinrich and Bugnyar 2005). Their intelligence, behavioral flexibility, and omnivorous diet allow ravens to adapt to many conditions and innovatively learn foraging behaviors, especially in context with human landscape changes and food sources (e.g., Ficken 1977, Andersson 1989, Heinrich 1995, Lefebvre et al. 1997). Ravens can also identify interconnections between stimuli and potential unseen food resources. For example, a controlled experiment in Wyoming found that Common Ravens learned to fly toward gunshots, but only in forested areas where the auditory stimuli would be most beneficial for locating carcasses or gut piles; they did not respond to other loud sounds like airhorns or slamming car doors (White 2005). In another study, ravens learned to follow researchers who were setting up artificial nests so they could immediately raid them (Vander Haegen et al. 2002)

Alternatives to Fisher\u27s Exact Test for Analyzing 2 X 2 Tables with Small Cell Sizes

Rice (1988a) presents an interesting test for analyzing 2 X 2 contingency tables in the smaller sample size situations. His motivation was to provide an alternative to Fisher\u27s exact test and his rationale was based on the application of a prior distribution to the probability of a success, 0, under the null hypothesis. We would like to briefly comment on these aspects of his paper and also discuss another alternative that was proposed a number of years ago

Evaluating and validating abundance monitoring methods in the absence of populations of known size: review and application to a passive tracking index

Rarely is it possible to obtain absolute numbers in free-ranging populations and although various direct and indirect methods are used to estimate abundance, few are validated against populations of known size. In this paper, we apply grounding, calibration and verification methods, used to validate mathematical models, to methods of estimating relative abundance. To illustrate how this might be done, we consider and evaluate the widely applied passive tracking index (PTI) methodology. Using published data, we examine the rationality of PTI methodology, how conceptually animal activity and abundance are related and how alternative methods are subject to similar biases or produce similar abundance estimates and trends.We then attune the method against populations representing a range of densities likely to be encountered in the field. Finally, we compare PTI trends against a prediction that adjacent populations of the same species will have similar abundance values and trends in activity. We show that while PTI abundance estimates are subject to environmental and behavioural stochasticity peculiar to each species, the PTI method and associated variance estimate showed high probability of detection, high precision of abundance values and, generally, low variability between surveys, and suggest that the PTI method applied using this procedure and for these species provides a sensitive and credible index of abundance. This same or similar validation approach can and should be applied to alternative relative abundance methods in order to demonstrate their credibility and justify their use

A visual method for indexing muskrat populations

The native range for muskrats (Ondatru zibethicus) includes much of North America, but they also have been introduced beyond their native range, including into the Fall River, California, where they have come into conflict with human interests. An easily applied method to assess their abundance is an important need for their management. We developed a muskrat visual index (MVI) to provide the information necessary to address this need. Observations were made at randomly located sites along the river. The number of muskrats observed during a 45 min period was recorded during the late afternoon peak activity time at each site on multiple days. The mean number observed over sites was calculated for each day. The index was the mean of the daily means. These design and measurement methods present valuable advantages over most traditional muskrat indexing methods in this environment. Traditional methods usually involve counting burrows or houses. However, in a relatively stable environment such as along the Fall River, muskrat burrows and houses tend to be long-lasting structures, making acute changes in population difficult to detect by there methods. Examining these structures for activity can be time-consuming and labor-intensive. Of particular importance, the statistical properties inherent to the MVI data structure permit calculation of standard errors, confidence intervals and statistical tests allowing quantitative comparisons among MVI values. Development of a management program for muskrats on the Fall River will require understanding of muskrat population fluctuations and densities, as well as knowledge of the effectiveness (short- and long-term) of control strategies. Here we develop a useful method, derive its statistical properties, and present baseline information for managing muskrats along the Fall River

Prioritizing Management and Research Actions against Invasive Reptiles in Florida: A Collaboration by an Expert Panel

Florida has more introduced animals than any other region of the U.S. and also ranks high in this respect globally. Given Florida\u27s climate, it is no coincidence that a large proportion of Florida’s invasive vertebrate species are reptiles and amphibians. Exotic snakes, lizards, frogs, turtles, and crocodilians are all breeding in Florida. The largest snakes in Florida are constrictors from other continents, and the five largest lizard species breeding in Florida are from Africa, South America, and Central America. Establishment of non-native reptiles and amphibians has been documented in Florida for over 135 years, and the rate of invasive reptile species establishment has been accelerating in the last half century. Florida currently has 16 native lizard species compared to 43 invasive species of lizard established and breeding in the state. Florida\u27s subtropical climate in the south, its major ports of entry for many wildlife species to the U.S. (both legal and illegal), its thriving captive wildlife industry, and its location in an area of destructive hurricanes that can release captive animals make the state particularly susceptible to the introduction and establishment of a wide range of species. Moreover, Florida is isolated from land with similar climates, resulting in the state\u27s vertebrates typically originating in the southeast U.S. at the southern extremes of their range. Invaders to Florida therefore find relatively fewer native species to contend with than in most tropical/subtropical locations