What Animals are Marked and Recaptured?
It is often necessary for biologists and wildlife managers to estimate the population size of wild animal species. Knowing whether population is increasing or decreasing is integral to conservation management, and essential in cases of threatened or endangered species. However, it is often impossible to obtain a complete count of animals in their natural environments. As a result, various methods for estimating population size have been devised.
Methods for Estimating Population Size
The simplest method for estimating population size is counting individuals by various means in random designated areas called quadrats. Another, known as the transect method, involves method involves counting individuals in larger areas in which quadrats are placed at fixed intervals.1
The Mark-Recapture technique is a method that falls between these two.2 This involves marking a subset of a population, followed by later counts on the relative numbers of marked (recaptured) and unmarked (not previously captured) individuals. This method is considered to be more precise than an arbitrarily-derived census in which no animals are marked, but involves less time and expense than a comprehensive marking and tracking effort.
What is Mark-Recapture?
The Mark-Recapture method is used for all manner of wildlife species, and is particularly effective with populations of smaller animals, such as birds, fish and small invertebrates. It is currently the most popular way of estimating the size of a population, and is widely used by fish and wildlife managers to estimate population sizes before fishing or hunting seasons.2
Mark-Recapture involves capturing and marking a number of individual animals in a population and returning them to that population. Groups of animals are subsequently captured, which necessarily include some of those that were captured initially. The ratios that arise from the captured and recaptured animals form the basis for estimating the size of the population at the time of the marking and release. Marking materials can consist of a wide range of materials, such as paint, metal bands, metal clips, collars, ear tags and radio tags.
The design of a Mark-Recapture study is important, and helps to determine which model is appropriate for estimating population size.1 One assumption that is made when estimating the size of population via Mark-Recapture is that the population is closed. A closed population remains constant in size and composition throughout a study, whereas an open population is subject to animals leaving and entering the population through births, deaths, emigration, and immigration. Thus, analyzing data of open populations is often complicated due to animals leaving and entering populations.
Interested in learning more about safe capture? The San Diego Zoo now offers courses in safe capture techniques and best practices. Learn reliable, safe, and effective techniques for the species you work with and the scenarios you encounter!
About NexGen Pharmaceuticals
NexGen Pharmaceuticals is an industry-leading veterinary compounding pharmacy, offering sterile and non-sterile compounding services nationwide. Unlike other veterinary compounding pharmacies, NexGen focuses on drugs that are difficult to find or are no longer available due to manufacturer discontinuance or have yet to be offered commercially for veterinary applications, but which still serve a critical need for our customers. We also specialize in wildlife pharmaceuticals, including sedatives and their antagonists, offering many unique options to serve a wide array of zoo animal and wildlife immobilization and anesthesia requirements.
Our pharmacists are also encouraged to develop strong working relationships with our veterinarians in order to better care for veterinary patients. Such relationships foster an ever-increasing knowledge base upon which pharmacists and veterinarians can draw, making both significantly more effective in their professional roles.
Disclaimer
The information contained in this blog post is general in nature and is intended for use as an informational aid. It does not cover all possible uses, actions, precautions, side effects, or interactions of the medications shown, nor is the information intended as medical advice or diagnosis for individual health problems or for making an evaluation as to the risks and benefits of using a particular medication. You should consult your veterinarian about diagnosis and treatment of any health problems. Information and statements have not been evaluated by the Food and Drug Administration ("FDA"), nor has the FDA approved the medications to diagnose, cure or prevent disease. Medications compounded by NexGen Pharmaceuticals are prepared at the direction of a veterinarian. NexGen Pharmaceuticals compounded veterinary preparations are not intended for use in food and food-producing animals.
NexGen Pharmaceuticals, LLC does not recommend, endorse or make any representation about the efficacy, appropriateness or suitability of any specific dosing, products, procedures, treatments, services, opinions, veterinary care providers or other information that may be contained in this blog post. NEXGEN PHARMACEUTICALS, LLC IS NOT RESPONSIBLE NOR LIABLE FOR ANY ADVICE, COURSE OF TREATMENT, DIAGNOSIS OR ANY OTHER INFORMATION, SERVICES OR PRODUCTS THAT YOU OBTAIN THROUGH THIS BLOG POST.