Comparing probability and non-probability sampling methods in ecstasy research : implications for the internet as a research tool

The usage of Ecstasy and related drug (ERD) has increasingly been the focus of epidemiological and other public health-related research. One of the more promising methods is the use of the Internet as a recruitment and survey tool.However, there remain methodological concerns and questions about representativeness. Three samples of ERD users in Melbourne, Australia surveyed in 2004 are compared in terms of a number of key demographic and drug use variables. The Internet, face-to-face, and probability
sampling methods appear to access similar but not identical groups of ERD users. Implications and limitations of the study are noted and future research is recommended.

Insights into the breeding behaviour and dispersal of the Powerful Owl (Ninox strenua) through the collection of shed feathers

The Powerful Owl is an elusive species inhabiting the forests of mainland eastern Australia. Obtaining crucial information on aspects of their breeding behaviour and dispersal has proven extremely difficult, even though other aspects of their ecology are well studied. Here we use molecular methods to investigate the breeding behaviour and dispersal of the Powerful Owl in two different habitats: highly fragmented forest along the urban fringe and continuous forest.DNA profiles of Powerful Owls were obtained predominately from shed feathers collected opportunistically between 1995 and 2006. Seven breeding pairs of Powerful Owls were identified, from which shed feathers were collected during 2003, 2004 and 2005. By comparing DNA profiles, one pair of Owls was found to have occupied the same breeding site for 10 years (1995–2005). The dispersal or movements of five offspring from this pair was also determined to be either of two scenarios: (1) the juvenile moves from the natal territory; however, isn’t breeding; and (2) the juvenile is recovered as part of a breeding pair. Two pairs of Owls breeding in the urban fringe habitat were closely related, but no incidences of extra-pair fertilisation were detected among pairs in either habitat. This study provides new information about the breeding behaviour and dispersal of the Powerful Owl, and shows the potential of using genetic data sourced from shed feathers for studying cryptic, rare or elusive species.

A comparison of the effectiveness of camera trapping and live trapping for sampling terrestrial small-mammal communities

Context. There is an increasing reliance on the use of camera-trap technologies for surveys of medium to large terrestrial mammals. Camera trapping may, however, also have significant applications for broad-scale surveys of small mammals.
Aims. The present study aims to compare results from camera-trapping surveys to those of the more traditional live trapping techniques. Specifically, it aims to test the effectiveness of the techniques for detecting species, and the cost effectiveness of both approaches.
Methods. Surveys were conducted across 36 sites in the Grampians National Park, Victoria, Australia, between April and July 2009. At each site, independent surveys were conducted for small mammals by using a combination of Elliot and cage trapping, then camera trapping. Results for the two different approaches were compared for both their ability to generate small-mammal presence data and their cost effectiveness.
Key results. Camera-trapping surveys of 36 sites in the Grampians National Park compared favourably with those of live trapping surveys. Similar species were detected across the sites, and camera trapping was a considerably more cost effective than live trapping.
Conclusions. Camera-trapping surveys of small terrestrial mammals may provide a new and cost-effective technique for surveying terrestrial small mammals. This is particularly the case when presence data are the main requirement of the survey, with no requirement to capture and tag animals.
Implications. Given the cost-effective nature of camera trapping, there is potential to use this approach to increase the level of replication and spatial coverage of small-mammal surveys. Improving the replication and spatial coverage of studies has the potential to significantly increase the scope of research questions that can be asked, thus providing the potential to improve wildlife management.

Estimating process capability index Cpm using a bootstrap sequential sampling procedure

Construction of a confidence interval for process capability index CPM is often based on a normal approximation with fixed sample size. In this article, we describe a different approach in constructing a fixed-width confidence interval for process capability index CPM with a preassigned accuracy by using a combination of bootstrap and sequential sampling schemes. The optimal sample size required to achieve a preassigned confidence level is obtained using both two-stage and modified two-stage sequential procedures. The procedure developed is also validated using an extensive simulation study.

Male mate-searching strategies and female cues: how do male guppies find receptive females?

Locating potential mates is critical to mating. We studied males’ association with females and mate-searching patterns in the guppy, Poecilia reticulata, a promiscuous live-bearer. In the field, we examined whether male guppies respond differently to a shoal of conspecific fish based on the members of the shoal. We found that more males were attracted to shoals that contained receptive females than to shoals of nonreceptive females or males. We also conducted laboratory experiments to investigate how males use olfactory cues of nonreceptive and receptive females to search for and associate with females. We gave males the option to associate with nonreceptive females when olfactory cues of receptive or nonreceptive females were present and absent, and when olfactory cues were presented alone. Males associated with females most strongly when both cues were presented simultaneously, but when cues were presented separately males’ association with females differed with respect to the olfactory cues that were added. Males associated with females equally with visual and olfactory cues presented separately when the odour cues were from receptive females. However, when the odour cues were from nonreceptive females, males associated with females less with olfactory than visual cues. Searching activity increased when males had access only to olfactory cues. Taken together these results suggest that olfactory cues influence males’ association with females and searching behaviour, and these changes in behaviour are likely to maximize a male’s opportunity to encounter receptive females.

Are most samples of animals systematically biased? Consistent individual trait differences bias samples despite random sampling

Sampling animals from the wild for study is something nearly every biologist has done, but despite our best efforts to obtain random samples of animals, ‘hidden’ trait biases may still exist. For example, consistent behavioral traits can affect trappability/catchability, independent of obvious factors such as size and gender, and these traits are often correlated with other repeatable physiological and/or life history traits. If so, systematic sampling bias may exist for any of these traits. The extent to which this is a problem, of course, depends on the magnitude of bias, which is presently unknown because the underlying trait distributions in populations are usually unknown, or unknowable. Indeed, our present knowledge about sampling bias comes from samples (not complete population censuses), which can possess bias to begin with. I had the unique opportunity to create naturalized populations of fish by seeding each of four small fishless lakes with equal densities of slow-, intermediate-, and fast-growing fish. Using sampling methods that are not size-selective, I observed that fast-growing fish were up to two-times more likely to be sampled than slower-growing fish. This indicates substantial and systematic bias with respect to an important life history trait (growth rate). If correlations between behavioral, physiological and life-history traits are as widespread as the literature suggests, then many animal samples may be systematically biased with respect to these traits (e.g., when collecting animals for laboratory use), and affect our inferences about population structure and abundance. I conclude with a discussion on ways to minimize sampling bias for particular physiological/behavioral/life-history types within animal populations.

The sampling and remix dilemma: what is the role of moral rights in the encouragement and regulation of derivative creativity

The borrowing and rearrangement of musical content, especially in the digital context, raises difficult questions for copyright law. There is significant community support for a loosening of the restrictions on the derivative (and particularly creative) use of copyright material. Law reform is called for. This paper discusses the possible introduction of a new exception to copyright infringement but notes that in the drafting of any such exception not only the economic rights but also the moral rights of the originating author need to be taken into account.