Monitoring Biodiversity: Tools and Techniques
Exploring modern methods to track and protect wildlife populations effectively.
― 6 min read
Table of Contents
- Modern Tools for Wildlife Monitoring
- Using Models to Analyze Wildlife Data
- Occupancy Models Explained
- The Challenge of Discretization in Occupancy Models
- Continuous-time Models vs. Discrete-time Models
- Examining Model Performance
- Case Study: Lynx Monitoring
- Choosing the Right Occupancy Model
- The Importance of Data Quality and Collection Period
- Future of Biodiversity Monitoring
- Conclusion
- Original Source
Biodiversity is the variety of life in the world, and it is decreasing at an alarming rate. This decline has raised concerns about how we need to understand what is causing this loss so that we can protect nature better. As regulations and guidelines are being strengthened to ensure that biodiversity does not continue to decrease, there is an increasing need for monitoring wildlife. At the same time, advances in technology mean that we now have better and more affordable tools to help us monitor and collect data about wildlife.
Modern Tools for Wildlife Monitoring
One such tool is Sensors, which include things like camera traps and autonomous recording units. These devices are becoming more common and are an important way to address ecological challenges. They offer advantages over traditional methods of observing wildlife. For example, they do not disturb the animals, they can be less expensive, and they can be placed in hard-to-reach areas to observe shy or elusive animals. They also help with collecting consistent data over time.
Because of these benefits, sensors are now recommended in policies related to biodiversity. For instance, organizations are looking to combine sensor data with large datasets and artificial intelligence to gain deeper insights into animal species and their habitats.
Using Models to Analyze Wildlife Data
To make sense of the data collected from wildlife monitoring, ecologists often use models. These models estimate things like whether a species is present in a given area or how many individuals are there. They do so by looking at relationships with environmental factors. There are models that focus on a specific species as well as models that consider multiple species at once.
A specific type of model that has gained prominence is the occupancy model, which estimates whether animals are present in a particular spot. For example, if a camera trap takes a picture of a deer, we say that location is "occupied." The model can then be used to estimate how many sites in a region are occupied by that species.
Occupancy Models Explained
Occupancy models include two main parts. The first part looks at the actual presence of the species, while the second part considers the possibility that the species may not be detected even if it is there. This second part acknowledges that sometimes animals are present but go unseen due to various reasons, like being hidden or not moving in front of the camera.
Standard occupancy models usually analyze data gathered at certain times, like during short surveys. However, with the increasing use of sensors, data collection can happen continuously over long periods. This means that models need to adapt to handle this continuous flow of information.
The Challenge of Discretization in Occupancy Models
When using sensors to collect data, researchers often need to break this continuous data into smaller time intervals. These smaller intervals can be called "sessions." The challenge is that the way researchers choose to create these sessions can significantly impact the results of the models.
If researchers choose to make sessions too long, they may lose details that could affect the accuracy of the model. On the other hand, if the sessions are too short, they might not gather enough information. This can make the model less reliable.
Continuous-time Models vs. Discrete-time Models
There are two main types of models to choose from: continuous-time models and discrete-time models. Continuous-time models take advantage of the continuous data collected by sensors. They allow researchers to look more closely at how animal presence changes over time, which can provide valuable insights.
Discrete-time models, on the other hand, aggregate data into those smaller time intervals. While these models have been used for a long time, they can sometimes oversimplify the data and overlook important details.
Each type of model has its pros and cons. Discretizing data simplifies it, but it can also obscure variations. Continuous-time models may offer a richer analysis, but they can be more complex to use.
Examining Model Performance
In studies that compare continuous and discrete models, researchers often investigate different scenarios where animals might be hard to detect. This is important because when species are elusive, the models might struggle to provide accurate occupancy estimates.
To assess how well these models perform, researchers simulate various occupancy scenarios. For each model, they measure how accurately they can estimate the actual occupancy probability. This kind of evaluation helps identify which models work best under certain conditions.
Case Study: Lynx Monitoring
To illustrate the differences between these models, researchers analyzed data from lynx monitoring in a specific area. They used five different occupancy models and compared their estimates of lynx occupancy. The models produced similar results, suggesting that they could reliably estimate lynx presence despite the challenges of dealing with elusive species.
For easily detectable species, all models showed good performance, but when it came to highly elusive species, there were noticeable differences. The models had various degrees of bias and overall accuracy, highlighting the importance of choosing the right model based on the species being monitored.
Choosing the Right Occupancy Model
When selecting an occupancy model, researchers must consider several factors. For species that are easy to detect, simpler models may suffice. These models are typically more straightforward and can yield good estimates of occupancy.
However, for more complex studies focusing on animal behavior or activity patterns, continuous-time models may provide greater value. These models can capture finer details of animal movements and interactions that discrete models may overlook.
The Importance of Data Quality and Collection Period
Collecting high-quality data is crucial for any wildlife monitoring effort. If a species is highly elusive, extending the monitoring period can help gather more data, improving model performance. In cases where gathering more data isn't possible, researchers should be cautious in interpreting the results since they may not accurately reflect reality.
When working with continuous data, it is important to consider how detection rates impact occupancy estimates. For instance, a model that accounts for variations in detection rates can provide more reliable insights into how often animals are seen.
Future of Biodiversity Monitoring
As technology continues to improve, we can expect more advancements in wildlife monitoring tools. Automated systems that use artificial intelligence to identify species in photos or recordings are becoming more common. Combining these tools with the right statistical models could lead to more efficient and accurate monitoring of biodiversity.
Researchers should remain open to using various models in their analysis. This not only helps validate results but also allows for flexibility when dealing with different species and monitoring challenges. By continuing to refine their approaches, researchers can contribute to a better understanding of the animals and ecosystems they study.
Conclusion
The decline in biodiversity is a critical issue that needs immediate attention. Continuous monitoring and the use of appropriate modeling techniques are essential for understanding and addressing this issue. By utilizing both modern technology and robust statistical methods, we can better safeguard our natural world and ensure the survival of diverse species for future generations.
Title: Analysing biodiversity observation data collected in continuous time: Should we use discrete- or continuous-time occupancy models?
Abstract: O_LIBiodiversity monitoring is undergoing a revolution, with fauna observations data being increasingly gathered continuously over extended periods, through sensors like camera traps and acoustic recorders, or via opportunistic observations. These data are often analysed with discrete-time ecological models, requiring the transformation of continuously collected data into arbitrarily chosen non-independent discrete time intervals. To overcome this issue, ecologists are increasingly turning to the existing continuous-time models in the literature. Closer to the real detection process, they are lesser known than discrete-time models, not always easily accessible, and can be more complex. Focusing on occupancy models, a type of species distribution models, we asked ourselves: Should we dedicate time and effort to learning and using these continuous-time models, or can we go on using discrete-time models? C_LIO_LIWe conducted a comparative simulation study using data generated within a continuous-time framework. We assessed the performance of five static occupancy models with varying detection processes: discrete detection/non-detection process, discrete count process, continuous-time Poisson process, and two types of modulated Poisson processes. Our goal was to assess their abilities to estimate occupancy probability with continuously collected data. We applied all models to empirical lynx data as an illustrative example. C_LIO_LIIn scenarios with easily detectable animals, we found that all models accurately estimated occupancy. All models reached their limits with highly elusive animals. Variation in discretisation intervals had minimal impact on the discrete models capacity to estimate occupancy accurately. C_LIO_LIOur study underscores that opting for continuous-time models with an increased number of parameters, aiming to get closer to the sensor detection process, may not offer substantial advantages over simpler models when the sole aim is to accurately estimate occupancy. Model choice can thus be driven by practical considerations such as data availability or implementation time. However, occupancy models can encompass goals beyond estimating occupancy probability. Continuous-time models, particularly those considering temporal variations in detection, can offer valuable insights into specific species behaviour and broader ecological inquiries. We hope that our findings offer valuable guidance for researchers and practitioners working with continuously collected data in wildlife monitoring and modelling. C_LI
Authors: Léa Pautrel, S. Moulherat, O. Gimenez, M.-P. Etienne
Last Update: 2024-02-27 00:00:00
Language: English
Source URL: https://www.biorxiv.org/content/10.1101/2023.11.17.567350
Source PDF: https://www.biorxiv.org/content/10.1101/2023.11.17.567350.full.pdf
Licence: https://creativecommons.org/licenses/by/4.0/
Changes: This summary was created with assistance from AI and may have inaccuracies. For accurate information, please refer to the original source documents linked here.
Thank you to biorxiv for use of its open access interoperability.