Studying Wild Bats with Small On-Board Sound and Movement Recorders

Post provided by LAURA STIDSHOLT

Releasing a female Greater mouse-eared bat with the tag in collaboration with Holger Goerlitz, Stefan Greif and Yossi Yovel. ©Stefan Greif

The way that bats acrobatically navigate and forage in complete darkness has grasped the interest of scientists since the 18th century. These seemingly exotic animals make up one in four mammalian species and play important roles in many ecosystems across the globe from rainforests to deserts. Yet, their elusive ways continue to fascinate and frighten people even today. Over the last 200 years, dedicated scientists have worked to uncover how bats hunt and navigate using only their voice and ears while flying at high speed in complete darkness. Still, the inaccessible lifestyle of these small, nocturnal fliers continues to challenge what we know about their activities in the wild.

Understanding the impact bats have on their ecosystems – for example how many insects a bat catches per night – has still not been directly measured. Most of our knowledge on the natural behaviour and foraging ecology is based on elaborate, but ground-based experiments carried out in the wild. These experiments generally track their behaviour using radio-telemetry, record snapshots of their emitted echolocation calls with microphones, or involve extensive observations. Continue reading

What Biases Could Your Sampling Methods Add to Your Data?

Post provided by ROGER HO LEE

這篇博客文章也有中文版

Have you ever gone fishing? If so, you may have had the experience of not catching any fish, while the person next to you got plenty. If you walked along the pier or bank, you may have seen that other fishermen and -women caught fish of various shapes and sizes. You’d soon realise that each person was using a different set of equipment and baits, and of course, that the anglers differed in their skills and experience. Beneath the water were many fish, but whether you could catch them, or which species could even be caught, all depended on your fishing method, as well as where and how the fish you were targeting lived.

Designing Sampling Protocols

Head view of different ant species found in Hong Kong and further in SE Asia.

Head view of different ant species found in Hong Kong and further in South East Asia.

This is a lot like the situation that ecologists often face when designing sampling protocols for field surveys. While a comprehensive survey will yield the most complete information, few of us have the resources to capture every member of the community we’re studying. So, we take representative samples instead. But the method(s) used for sampling will only allow us to collect a subset of the species which are present. This selection of the species is not random per se – it’s dependent on species’ life history. Continue reading

採樣方法會帶來怎樣的數據偏差?

作者:李灝

This blog post is also available in English

你有釣魚的經驗嗎?若有的話,以下的經歷對你應該不會陌生。自己釣了大半天,魚杆動也沒動過,但身旁的釣手卻滿載而歸。感到灰心時,你沿著碼頭或岸邊巡視,你看到其他人的魚獲大大小小的也有﹑形態不同的的也有。心裡被疑惑與不甘的思緒纏繞著的一刻,你突然意識到每個人都在使用不同的釣具和魚餌(當然每位垂釣者的技能和經驗也不同)。在水中有各種各樣的魚,但你能否釣到牠們,或者釣到那一些品種,都取決於你釣魚的方法,以及你目標魚種的活動範圍和生活方式。

採樣方案的設計

Head view of different ant species found in Hong Kong and further in SE Asia.

香港和東南亞地區的螞蟻品種。

上述的經歷與生態學家在設計野外調查時所遇到的情況非常相似。雖然全面的調查能取得最完整的資料,但我們很少會有充足的資源去完整地採集整個物種群落。取而代之的是我們只能採集一部份的物種來作寫照。值得我們留意的是每種採樣方法只允許我們收集到群落中的某些物種;這些物種不是隨機地被選中,而是取決於物種的生活史。 Continue reading

How Can Understanding Animal Behaviour Help Support Wildlife Conservation?

Below is a press release about the Methods in Ecology and Evolution article ‘A novel biomechanical approach for animal behaviour recognition using accelerometers‘ taken from the EPFL.

©Arpat Ozgul, University of Zurich

Researchers from EPFL and the University of Zurich have developed a model that uses data from sensors worn by meerkats to gain a more detailed picture of how animals behave in the wild.

Advancement in sensor technologies has meant that field biologists are now collecting a growing mass of ever more precise data on animal behaviour. Yet there is currently no standardised method for determining exactly how to interpret these signals. Take meerkats, for instance. A signal that the animal is active could mean that it is moving; alternatively, it could indicate that it is digging in search of its favourite prey, scorpions. Likewise, an immobile meerkat could be resting – or keeping watch.

In an effort to answer these questions, researchers from EPFL’s School of Engineering Laboratory of Movement Analysis and Measurement (LMAM) teamed up with colleagues from the University of Zurich’s Population Ecology Research Group to develop a behavior recognition model. The research was conducted in affiliation with the Kalahari Research Centre. Continue reading

Phylogenetic Tip Rates: How Well Can We Estimate Diversification?

Post provided by Pascal Title and Dan Rabosky

Analyzing diversification rate heterogeneity across phylogenies allows us to explore all manner of questions, including why Australia has such an incredible diversity of lizards and snakes.

Analyzing diversification rate heterogeneity across phylogenies allows us to explore all manner of questions, including why Australia has such an incredible diversity of lizards and snakes.

Within the tree of life there are differences in speciation and extinction rates over time and across lineages. Biologists have long been interested in how speciation rates change as a function of ecological opportunity or whether key innovations lead to increases in the rate of speciation. Exploring this rate variation and examining how clades differ in terms of their diversification dynamics can help us to understand why species diversity varies so dramatically in time and space. Learning more about the relationship between traits and diversification rates is especially important because it has the potential to reveal the causes of pervasive variation in species richness among clades and across geographic regions.

Several different classes of methods are available for studying the effects of species traits on lineage diversification rates. These include state-dependent diversification models (e.g., BiSSE, QuaSSE, HiSSE) and several non-model-based approaches. In our article – ‘Tip rates, phylogenies and diversification: What are we estimating, and how good are the estimates?’ – we assessed the accuracy of a number of model-free metrics (the DR statistic, node density metric, inverse of terminal branch lengths) and model-based approaches (Bayesian Analysis of Macroevolutionary Mixtures, BAMM) to determine how they perform under a variety of different types of rate heterogeneity. The “tip rates” using these approaches have become widely used for a few reasons, including ease of computation and how easy it is to pair them with other types of data. Continue reading

New Technologies Could Help Conservationists Keep Better Track of Serengeti Wildebeest Herds

Below is a press release about the Methods in Ecology and Evolution article ‘A comparison of deep learning and citizen science techniques for counting wildlife in aerial survey images‘ taken from the University of Glasgow.

A wildebeest herd in the Serengeti. ©Daniel Rosengren

A wildebeest herd in the Serengeti. ©Daniel Rosengren

Mathematicians and conservationists from the UK, Africa and the United States have used machine-learning and citizen science techniques to accurately count wildebeest in the Serengeti National Park in Tanzania more rapidly than is possible using traditional methods.

Evaluating wildebeest abundance is currently extremely costly and time-intensive, requiring manual counts of animals in thousands of aerial photographs of their habitats. From those counts, which can take months to complete, wildlife researchers use statistical estimates to determine the size of the population. Detecting changes in the population helps wildlife managers make more informed decisions about how best to keep herds healthy and sustainable. Continue reading

Quantifying Animal Movement from Videos

Quantifying animal movement is central to research spanning a variety of topics. It’s an important area of study for behavioural ecologists, evolutionary biologists, ecotoxicologists and many more. There are a lot of ways to track animals, but they’re often difficult, especially for people who don’t have a strong background in programming.

Vivek Hari SridharDominique G. Roche and Simon Gingins have developed a new, simple software to help with this though: Tracktor. This package provides researchers with a free, efficient, markerless video-based tracking solution to analyse animal movement of single individuals and groups.

Vivek and Simon explain the features and strengths of Tracktor in this new video:

Read the full Methods in Ecology and Evolution article ‘Tracktor: Image‐based automated tracking of animal movement and behaviour
(No Subscription Required).

Download and start using Tracktor via GitHub.

Field Work on a Shoestring: Using Consumer Technology as an Early Career Researcher

Post provided by CARLOS A. DE LA ROSA

Esta entrada de blog también está disponible en español

Champagne Tastes on a Beer Budget

Freshly outfitted with a VACAMS camera and GPS unit, #1691 heads off into the forest with her calf. ©Carlos A. de la Rosa

Freshly outfitted with a VACAMS camera and GPS unit, #1691 heads off into the forest with her calf. ©Carlos A. de la Rosa

There’s a frustrating yin and yang to biological research: motivated by curiosity and imagination, we often find ourselves instead defined by limitations. Some of these are fundamental human conditions. The spectrum of light detectable by human eyes, for example, means we can never see a flower the way a bee sees it. Others limitations, like funding and time, are realities of modern-day social and economic systems.

Early career researchers (ECRs) starting new projects and delving into new research systems must be especially creative to overcome the odds. Large grants can be transformative, giving a research group the equipment and resources to complete a study, but they’re tough to get. Inexperienced ECRs are at a disadvantage when competing against battle-hardened investigators with years of grant writing experience. Small grants of up to about $5000 USD, on the other hand, are comparatively easy to find. So, how can ECRs make the most of small, intermittent sources of funding?

I found myself faced with this question in the second year of my PhD field work. Continue reading