Techniques and Technologies for Studying Seabirds Flashcards
Why is understanding at-sea habitat use critical to understanding seabird biology, movement and conservation in seabirds?
Outside of the breeding system seabirds spend most of their time at sea.
Movement
Any tracked movement that is not migration
Migration
Implies periodic two way movement to and from a given area
Why do seabirds migrate?
- To separate breeding and feeding grounds (some breeding grounds may not be as productive as feeding grounds)
- Follow environmental conditions and foraging movements
What are the two different types of foraging movements?
- Pelagic hunters (not breeding)
- Central-place foragers (breeding)
Describe central place foragers
Always return to a central place when foraging (“home-base”)
Why is this a huge constraint
what can influence foraging movements?
Oceanography: Foraging movements are closely tied to physical oceanographic features (ex: fronts, upwellings, sea mounts etc.)
Why study animal movement?
To understand:
- Distribution and habitat use
- Foraging search strategies
- Animal navigation
- Spread of diseases
- Conservation biology
What are challenges in studying seabird movements?
- They live most of their lives offshore
- Most sampling is conducted at breeding locations (Why is this a problem?)
- Difficult to catch at foraging locations
- Differential habitat use by sex, age, and class (Breeding adults and chicks spend most of their time at the breeding colonies, juveniles and non-breeding adults spend most of their time at sea)
- Tags must be be light weight so that they do not weigh birds down
- Important movements occur at depth but observations take place at the surface
- Physical environment is hard on tracking instruments
Banding
- Important for tracking same individual bird
- No data transmission (just recognition)
What are some limitations of bird banding?
Banding is not an accurate depiction of birds full activity
Time Depth Recorders (TDRs)
- Developed first in the 1960s (Gerry Kooyman)
- What depth is the bird diving at and at what time (the only info is time and depth)
VHF Tags
- Radio tags (before GPS)
- Tag sends out signals that get picked up by a receiver at fixed stations when bird flies by (you are not actively tracking the bird)
What are limitations of VHF tags
Low spatial resolution
What are commonly used tagging technologies today?
- Satellite tags
- GPS tags
- GLS tags
- Activity loggers
- Accelerometers
- Magnetometers
What are limitations of PTT tags?
- The battery life is not long
- They are big (limited to bigger bird species)
- Low / uneven temporal resolution
- Argos system is limited to the number of positional fixes that can be taken per day
- Positional accuracy of Argos varies
Argos Satellites
- Provide info. on animal movement and oceanographic features
- Actively transmit data
- Data collection and relay system that provides global coverage by “piggy backing” on polar-orbiting satellites
- Used since late 1980s
- Provides data on wide variety of applications
Icarus Satellite
- Actively transmits data
- International Cooperation for Animal Research Using Space
- Satellite based
- Tracks migratory patterns of animals
- Allows the use of trackers that do not require a strong signal and can therefore be smaller (Can tag and track smaller animals)
Archival Tags
- Tags must be physically recovered (most likely during next breeding season)
- Record detailed movement or activity data (ex: speed, depth and temperature)
GPS Tags
- High spatial resolution
- Archival (must be retrieved to collect data)
- Can be combined with Argos or GSM
Geolocator Tags (GLS Tags)
- Utilize light to calculate birds longitude and latitude
- Can track seabird movements for long periods (several years)
- Not as accurate as GPS or ARGOS
- Cheap and small
What are some limitations of GLS tags?
- Low spatial resolution
- Only good at measuring broad-scale migration patterns
Activity or Immersion Loggers
- Wet/dry sensor
- Indicates if a bird is in flight or in water (foraging)
- Can be used with GPS tags to identify foraging locations
What are some limitations of activity or immersion loggers?
Must be combined with tracking data to establish high resolution movements
Accelerometer
- Measures change in velocity of the body over time
- Provided detailed high resolution information on 3D movements
- Improvements in size and weight have allowed them to be deployed on smaller seabirds
What are some limitations of accelerometers?
- Limited battery life
- Short duration deployments only
What are accelerometers typically used for?
- Examine specific behaviors (ex: flapping flight)
- To estimate energetic expenditure
Magnetometers
- Can identify the heading of a bird (North or South)
- Ex: Albatross dynamic flight
What effects do tags have on seabirds?
Tags can affect:
- Movement
- Behavior
- Health
Explain why tagging is considered to be data rich?
- It is easier to get money (funding) for tagging seabirds (data collection) than it is to analyze that data
Describe stable isotope analysis in tissues
- Can be conducted on different tissues ( skin, egg yolk, bone etc.)
- Measurements of tissues from the same individual can be used to provide dietary information over different time scales
- Metabolically inactive tissues (hair, skin, whiskers, nails, feathers etc.) reflect diet only during growth period
How can stable isotopes be used to trace animal migrations?
- Foodweb isotopic signatures are reflected in the tissues of organisms
- Isotopic signatures can vary spatially
- Organisms moving between distinct foodwebs carry information on the location of previous feeding grounds for periods that depend on the turnover rates for the tissue of interest (ex: bones have a longer turnover rate than blood)
What is an isoscape?
A map that tells you weal habitat birds are feeding in
How can mercury be used to track habitat use?
- Methylmercury accumulates in aquatic but not terrestrial foods
- Can identify terrestrial vs. marine foraging habitats
Eularian tagging technique
- Fixed in space
- Can gain information about a large number of individuals at a particular location
Lagrangian tagging technique
- Moving with an individual
- Can gather information about a small number of individuals across a large area
What are the advantages of studying seabirds at breeding colonies?
- Gain information on how individual level behavior translates into population processes
What techniques can be used to study seabirds at breeding colonies?
- Nest balances
- Egg loggers
- Autonomous acoustic sensors
- Radar
Nest balances
- Remotely measures chick (or adult) mass between feedings (can quantify meal mass)
- Can learn about meal mass at different foraging locations for different trip durations when combined with tracking studies
Egg loggers
- Egg turning and incubation are critical to embryo development and hatching success (how is this different between species and how does it impact reproductive success)
- Developed using 3D accelerometers, magnetometers, and temperature loggers
Autonomous acoustic sensors
- Record vocalizations
- Can estimate abundances
Radar
- Can study movements of seabirds for many years
- Useful for nocturnal species that return to nest sites at night
- Can be used to identify bird species
