[MARMAM] Fwd: Definition (or there lack of) of residency / site fidelity

Áine O'Shea osheaine at gmail.com
Mon Jul 1 09:36:46 PDT 2013


Hello everyone
Following a request I submitted to MARMAM last week regarding a definition
for residency / site fidelity, I have received some information which I
would like to share with the MARMAM site.

Here are the main points & recommendations I received from respondents:
(Please note, these are the respondants opinions & I am very grateful for
everyone who contributed)

   -  It varies and there is no standard definition
   - The term "site fidelity" is *borrowed* from studies of terrestrial
   taxa, and in many cases those animals (whether they're mammals, lizards
   etc.) have very narrow ranges and/or territories that are easily defined.
   This isn't the case with most cetaceans
   -   Residency is in the eye of the beholder
   - There's no easy place to draw the line
   -  Residency suggests that animals are almost always present within a
   specific area, while site fidelity means that animals always return to the
   same location. Animals can show both residency and site fidelity, or they
   can show site fidelity without residency (as is the case in many migratory
   species)
   - In both cases, the terms are scale-dependent; that is, whether you
   define an animal as showing residency or site fidelity will depend on the
   size of the area you are using as your sampling units (usually defined as a
   study area) e.g. an individual might not be resident in a study area that
   consists of a single bay, while it may be resident in a wider region
   - Similarly, for site fidelity, an animal may not repeatedly return to
   the exact same bay, but may return to the same general area each year, e.g.
   a humpback whale might not show site fidelity to the island of Maui, but
   may show site fidelity for the entire Hawaiian archipelago
   -  Both site fidelity and residency may be interpreted as somewhat human
   constructs imposed on animals based on how we view a specific area of
   interest, and in all cases, they should be accompanied by a specific
   definition of the spatial area to which they are being applied
   - Residency, and to a lesser extent site fidelity, are not particularly
   useful ecological concepts (the fact that there are no clear definitions is
   also an indicator of this). Instead, it would be better to use more
   ecologically-meaningful terms like home range (which captures all areas
   where an individual occurs and is based on its own distribution and not any
   human construct of a study area at a specific spatial scale)
   - Levels of site fidelity can also be captured within the home range
   concept by looking at core areas within the total home range (for example,
   areas where an animal spends 50% of its time), and these can be identified
   using kernel density estimates (KDEs)
   - There is no natural division between residents and visitors in the
   Bottlenose population, Adelaide - some are almost always seen, some seen
   many times, some quite a lot, some only occasionally, some rarely, etc.
   - The terms may be defined by the conductor of the study
   - The term residency depends on your research question and hypothesis
   - Read studies outside the taxon which may or may not shed more light on
   definition
   - There is no consistency in the definitions, as in most cases the
   definitions are based on the duration of the study and not in what the
   animals are doing
   -  The re-sighting pattern of dolphins will vary with time and if the
   study is short, their definition is not going to be very rigorous
   - The best definition of the terms, have been defined for dolphins
   studies conducted in Sarasota Bay, Florida, and Shark Bay, Australia – as
   they are the two longest running projects of wild dolphins in the world
   - One must be careful with definitions and understand that different
   species have different re-sighting patterns based on the way that their
   societies are organized
   - The site fidelity or residency is dependent of the frequency and
   amount of individuals surveyed
   -  The terms vary also, like residence time (occupancy), annual return
   rate (recapture rate) and site fidelity - they are not the same, but
   reflect a tendency of animals coming back / using a particular area, in a
   certain period
   - Specify individuals within the species, so you should document your
   identification process and results
   -  Specify GPS coordinates of location you are proving fidelity.  For
   example, resident Orcas may be loyal to a particular bay, cove, inlet while
   still being characterized by residents
   - Specify dates/time of year so you can connect with migration patterns
   and/or all other known factors for the species and individual
   - Specify criteria, i.e. how often does the animal return?  With what
   other animals does s/he aggregate?  For what duration?
   - The method of residency / site fidelity is only a tool, not the truth
   - Figure out if your definition is close to someone else’s and why
   - Be careful not to miss factors that can drive the coincidence and
   determine if the pattern is biologically meaningful
   -  Explain also the meaning of any level of variability you observe and
   how it may overlap with someone else’s definition and why you stick to one
   or the other
   -  Regardless of the definitions used, the level of understanding of
   site fidelity for any particular species/population depends both on the
   actual movement patterns of the animals and the methods used to study them

Hope this information is of use
Best Regards,
Áine

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*Á**ine*





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