Sampling Methods Part 3 PDF

SAMPLING METHODS PART III Biodiversity Management 1B  Recap from Last Week Sampling plant populations Quadrat method Calculating densities and population estimates Line intercept method Belt transect method Point-frequency intercept method Sampling ANIMAL populations 1) Trap...

SAMPLING METHODS PART III Biodiversity Management 1B  Recap from Last Week Sampling plant populations Quadrat method Calculating densities and population estimates Line intercept method Belt transect method Point-frequency intercept method Sampling ANIMAL populations 1) Trapping and collecting 2) Marking animals 3) Aging animals 4) Determining sex 5) Determining home range and territory 6) Estimating numbers  1) Trapping and collecting Flying insects Aquatic Soil Small animals in Birds and mammals organisms organisms vegetation Diurnal insects – Dip nets, bottom Varying funnel Sweep nets with Cannon nets, mist nets aerial nets, nets, wire-basket methods such frames (insects, heavy duty scraper nets, as Berlese or arboreal sweep nets plankton towing Tullgren amphibians and nets, trawl nets funnels reptiles), drag nets and seine nets Nocturnal Quadrats or Beating vegetation Live traps (wood or insects – Transects with sticks with wire), snap traps, ultraviolet light canvas collecting Sherman traps – traps traps, mercury- trays on the can be baited vapor light traps, ground Malaise trap Underwater Traps with sticky photography or surfaces, pitfall videography traps  Trapping and collecting Malaise trap Cannon net Live trap Seine net Berlese-Tullgren funnel  2) Marking animals Used to distinguish: - certain members of a population at a future date - recognize individuals from others - study movements - estimate populations by mark- recapture  2) Marking animals Arthropods Fish Frogs, Birds Small Larger and snails toads, mammals animals salamanders , etc Quick drying Tags such as Toe clipping Serially Toe clipping, Fur clipping, cellulose Strap tags, numbered ear notching, tattooing, paint, for stream or aluminum fur clipping, dyes aquatic pennant bands, tattooing organisms – tags, plastic cellulose and ship-fouling tags, acoustic aluminum paint tags colored bands Clipping fins Snakes and Dying plumage GPS collars Strap tags or lizards – plastic discs removing attached to scales ears Radio or GPS collars  2) Marking animals Arthropods Fish Frogs, Birds Small Larger and snails toads, mammals animals salamanders , etc Quick drying Tags such as Toe clipping Serially Toe clipping, Fur clipping, cellulose Strap tags, numbered ear notching, tattooing, paint, for aquatic Many of these methods are stream or pennant aluminum bands, fur clipping, tattooing dyes organisms – ship-fouling invasive and some of them are tags, plastic tags, acoustic cellulose and aluminum paint unethical and have been phased tags colored bands Clipping fins Snakes and Dying plumage GPS collars Strap tags or out… toelizards clipping – etc. are less usedplastic discs removing attached to duescales to ethics involved ears Radio or GPS collars 2) Marking animals  3) Aging animals Challenging to obtain age structure of wild populations for many animals Most commonly used methods are available for fish, birds and certain mammals Fish – otolith/ear bones Birds – plumage development Mammals – reproductive organs, bone growth, skull measurements, growth rings on teeth, lens size in eyes  3) Aging animals Fish – otolith/ear bones Birds – plumage development Mammal teeth development  4) Determining sex For many animals gender/sex is easily determined due to clear morphological differences If differences aren’t immediately apparent then examining external genitalia are used for most mammals and for birds differences in plumage can be used  4) Determining sex Male Female Male Female 5) Determining Home Range and Territory Home range: the physical area in which an animal spends most of its time to obtain food, shelter, or find mates Territory: the area that an animal defends against other animals  5) Determining Home Range and Territory Several methods exist and some common methods include: - Home range mapping Involve capturing animals within a - Center of activity certain area to estimate home - Frequency of capture ranges - Territory Observation of behaviours Used to estimate - Radio tracking Radio frequencies used to track animals home ranges, - GPS tracking Satellite technology used to track centers of animals activity etc. 5) Determining Home Range and Territory Radio tracking GPS tracking  6) Estimating numbers Estimating animal population numbers is vital to the study of animals, especially in a conservation context Methods for estimating numbers or counting animals can be put into three categories: - True counts - Sampling estimates - Indices  Estimating numbers Animal counts for mobile animals have different requirements to plants and sedentary or slow-moving animals The counts are important for effective operational management of an area Counting animals also assists in ensuring that resource utilisation within an area is kept within ecological limits Counting animals in the context of management Management can only be done effectively if there is an objective in place Objectives will vary depending on the area in question Example: For a large game reserve (e.g. Kruger National Park) the objective might be to “retain the intrinsic value of the ecosystems found within the area” Example: For a smaller reserve (e.g. game farm) the objective might be to “manage the farm to ensure adequate financial return on the investment in property”  Operational Management Goals Operational management goals are nested under the main objective Example: An objective on a game farm might be to stock it with herbivores that occurred there naturally but are now absent An operational goal under this objective might be to introduce herbivores to the property and allow them to increase to carrying capacity (ecological limit)  The concept of Carrying Capacity Maximum number of individuals of a particular species that an environment can support or sustain  The concept of Carrying Capacity Maximum number of individuals of a particular species that an environment can support Example: Let’s say we have x amount of people and a fixed amount of food  The concept of Carrying Capacity Maximum number of individuals of a particular species that an environment can support As those people increase via reproduction, the amount of food decreases  The concept of Carrying Capacity Maximum number of individuals of a particular species that an environment can support Eventually, the food resource can only sustain so much before it is all gone  The concept of Carrying Capacity Carrying capacity is therefore, limited by: Food Water Shelter Appropriate space Disease Predation Climatic conditions If a population increases and approaches the carrying capacity, these resources will be limited If a population exceeds the carrying capacity, the deaths begin to outnumber the births and you will notice a decrease in the population size  6) Estimating numbers Estimating animal population numbers is vital to the study of animals, especially in a conservation context Methods for estimating numbers or counting animals can be put into three categories: - True counts - Sampling estimates Census Techniques - Indices  Sampling Considerations for Census Elements to consider Example Objective Determine the carrying capacity and keep track of the populations trend Size of habitat If area is too large to count animals on the ground, then use aerial surveys Type of habitat Consider topography, vegetation, waterways, etc. Animal characteristics Size, colour, posture, mobility, social behaviour Costs When and how to use expensive methods such as aircraft Skills Experience, work ethic, availability and quality of performance of staff Three main Census Techniques CENSUS 1. TRUE COUNTS 2. INDICES 3. SAMPLING COUNT ALL COUNT IN USE SIGNS SAMPLES TRUE POPULATION TRENDS EXTRAPOLATE NUMBERS Three main Census Techniques CENSUS 1. TRUE COUNTS 2. INDICES 3. SAMPLING COUNT ALL COUNT IN USE SIGNS SAMPLES TRUE POPULATION TRENDS EXTRAPOLATE NUMBERS  Four Main Principles to consider Counting Two options: Direct count (true or sampling census) or Indirect (indices) Location Three options: Air or ground, night or day, fixed point or not Tools Six criteria: - Observer mobility (foot, vehicle, etc) - Identification (binoculars, collars) - Enumeration (camera, video, data sheets) - Measurements (tapes, GPS, maps) - Capturing (traps, nets) - Data analysis (computers, calculators, etc) Estimation strategies Probability, accuracy, precision, bias, repeatability Three main Census Techniques CENSUS 1. TRUE COUNTS 2. INDICES 3. SAMPLING COUNT ALL COUNT IN USE SIGNS SAMPLES TRUE POPULATION TRENDS EXTRAPOLATE NUMBERS Census Technique 1. TRUE COUNTS All animals must be counted (need to consider mobility – not easy in hilly areas or dense vegetation) Systematic search of whole area Several limitations (resources, potential of missing species etc.) Better for large animals (e.g. Gemsbok in Kalahari using aircraft, or elephants or rhinos in Kruger) Three ground approaches can be used: i) Drive counts ii) Waterhole counts iii) Known group counts  1. TRUE COUNTS: i) Drive Counts Suitable for smaller wildlife ranches in open grassland or savanna regions (method can be modified for larger reserves) Main requirement – adequate number of observers to identify animals being counted  1. TRUE COUNTS: i) Drive Counts A number of observers spaced evenly over the area. Observers move through the area and count animals on one side (i.e. left or right) Total number recorded is added up at the end 1. TRUE COUNTS: ii) Waterhole Counts Observer at each waterhole Drinking behavior should be known Based on idea that all animals will drink at least once a day (not always true) → this could lead to underestimating numbers 1. TRUE COUNTS: ii) Waterhole Counts Need to consider that some animals may drink more than once and might be counted twice If there are many water holes or rivers as another source of water this method may be problematic – will influence the estimation of populations. How? Waterhole counts however, provide more information with regards to age, sex, behavior, etc. 1. TRUE COUNTS: iii) Known Group Counts Animals occurring in fixed herds or groups The size and composition of each group, each time it is encountered can provide an indication of how many individuals there are Useful to photograph individuals that have patterns that make them unique as it can allow for better population estimates 1. TRUE COUNTS: iii) Known Group Counts All groups identified and all animals in the group counted – all groups added up for total population Assumes home ranges do not change and that groups do not change during the census Can be subjective Prior knowledge of animals behaviour must be known Relatively easy to achieve if adequate resources available Three main Census Techniques CENSUS 1. TRUE COUNTS 2. INDICES 3. SAMPLING COUNT ALL COUNT IN USE SIGNS SAMPLES TRUE POPULATION TRENDS EXTRAPOLATE NUMBERS  2. INDICES Using other aspects as an indirect measure or indication of counts Involves counting droppings, footprints, dung heaps, calls (acoustics), etc. Identifying animals by differences in the frequency of their calls  2. INDICES Not very good for census due to low accuracy Mostly used for trends from one time to another, rather than actual counts What else could these indices be useful for?