LAS – les Herwig Leirs
Rodents = very large group
• Largest group of mammals
– About half of all the mammal species are rodent species
– 2277 species...
– All different
• Rats, mice, squirrels, hamsters, bevers, capybara’s …
• We think (European) that mice are smaller, and rats are larger à all around the world, there
are rodents in between this range, so, in many parts this difference does not exist; biologically
this does not have a meaning
Capture methods
Why would you do work in the field? Trapping rodents in the field?
à study objecNves
• Biodiversity, taxonomy and biogeography studies
– taxonomy = difference between different species
– biogeography = understand how the fauna in one area is similar or different to the
fauna in another area
• populaNon dynamics, demography
– demography = how is the populaNon composed (age, gender…)
• natural behaviour or physiology
– do the animal react different when it is in a different environment (reacNon in a forest
ßà reacNon in the lab)
• presence and transmission of pathogens
– pathogens present in wild populaNons? And how are they transmiPed?
• pest management research
– place where there is a conflict between humans and rodents à how can we undo the
damage?
– You should study the wild populaNons
• providing non-model animals for experiments
– animals that are different from the rodents
à Data collecNon
• external measurements, characterisNcs à how large is the animal, is it in a breeding condiNon,
territorial finds?
• (invasive) sampling of live animals
• post-mortem sampling
• museum voucher specimens à we trap animals, we preserve them and store them in a
museum as reference material (especially important when you are doing biodiversity work,
because oUen you don’t know which species you can find, and someNmes you find material
that is new à store this in a museum for other researchers as a reference)
Live trapping or kill trapping? à depends on the quesNon you have; both have advantages and
disadvantages
à Kill trapping:
• not animal experiment à capture it and it is immediately killed
• cheaper traps
• samples not affected by period alive in trap
– imagine you want to do a diet analysis, and you need the stomach content à you don’t
use a rodent that has been trapped for 4 hours, because then the composiNon will
differ
, • Ethical – welfare concerns
– quick, efficient killing required (± within 30 seconds + with enough power)
– appropriate size
– killing too many animals
o more than you need à hide more traps than animals than you need, but that
can cause welfare concerns
– killing non-target species
o problem if it is a protected species
o you will try to avoid killing animals when this is not necessary
• Many killing traps for pest control: not always pracNcal for research not much concern for
animal welfare
– E.g. bucket where the animal falls in à liquid (so they drown)
– Rat zapper: electric trip with a high voltage à rat is electrocuted when it enters
à Live trapping:
• capture-recapture/observaNon study
• no post-mortem samples needed
• fresh/undamaged post-mortem samples
• avoid leaving ectoparasites
– as long as the animal is alive, the ectoparasites are likely to stay present. ßà If you
trap an animal with a kill trap, then the parasites will leave and look for another host
• species protected or endangered
• non-target species can be released
• Ethical - welfare concerns
– capture stress
– temperature (e.g. in Tanzania: traps will be taken away before 9 am à we don’t want
the animals to be cooked ßà Belgium, in the winter, we will check every hour)
– food, water
– away from nest (mothers that need to lactate their pups à you don’t want to interfere
with the normal populaNon dynamics)
– removal from trap
• Ethical - welfare miNgaNons
– cover traps
– provide bedding, food
– limit Nme in trap
• Live traps – single capture
– ArNsanal wire mesh trap, Havahart trap, Sherman Light Folding Aluminium Trap,
TripTrap, arNsanal box trap, Longworth, Heslinga
• Live traps – mulNple capture
– Trap many more individuals (duh!)
– AddiNonal Ethical – welfare concerns
o intra/interspecific interacNons à if these are animals that don’t like each
other (one is the prey)
à can cause a lot of stress + species that normally live solitary, will fight in the
trap
o predaNon
o risk for drowning
Rodents = very large group
• Largest group of mammals
– About half of all the mammal species are rodent species
– 2277 species...
– All different
• Rats, mice, squirrels, hamsters, bevers, capybara’s …
• We think (European) that mice are smaller, and rats are larger à all around the world, there
are rodents in between this range, so, in many parts this difference does not exist; biologically
this does not have a meaning
Capture methods
Why would you do work in the field? Trapping rodents in the field?
à study objecNves
• Biodiversity, taxonomy and biogeography studies
– taxonomy = difference between different species
– biogeography = understand how the fauna in one area is similar or different to the
fauna in another area
• populaNon dynamics, demography
– demography = how is the populaNon composed (age, gender…)
• natural behaviour or physiology
– do the animal react different when it is in a different environment (reacNon in a forest
ßà reacNon in the lab)
• presence and transmission of pathogens
– pathogens present in wild populaNons? And how are they transmiPed?
• pest management research
– place where there is a conflict between humans and rodents à how can we undo the
damage?
– You should study the wild populaNons
• providing non-model animals for experiments
– animals that are different from the rodents
à Data collecNon
• external measurements, characterisNcs à how large is the animal, is it in a breeding condiNon,
territorial finds?
• (invasive) sampling of live animals
• post-mortem sampling
• museum voucher specimens à we trap animals, we preserve them and store them in a
museum as reference material (especially important when you are doing biodiversity work,
because oUen you don’t know which species you can find, and someNmes you find material
that is new à store this in a museum for other researchers as a reference)
Live trapping or kill trapping? à depends on the quesNon you have; both have advantages and
disadvantages
à Kill trapping:
• not animal experiment à capture it and it is immediately killed
• cheaper traps
• samples not affected by period alive in trap
– imagine you want to do a diet analysis, and you need the stomach content à you don’t
use a rodent that has been trapped for 4 hours, because then the composiNon will
differ
, • Ethical – welfare concerns
– quick, efficient killing required (± within 30 seconds + with enough power)
– appropriate size
– killing too many animals
o more than you need à hide more traps than animals than you need, but that
can cause welfare concerns
– killing non-target species
o problem if it is a protected species
o you will try to avoid killing animals when this is not necessary
• Many killing traps for pest control: not always pracNcal for research not much concern for
animal welfare
– E.g. bucket where the animal falls in à liquid (so they drown)
– Rat zapper: electric trip with a high voltage à rat is electrocuted when it enters
à Live trapping:
• capture-recapture/observaNon study
• no post-mortem samples needed
• fresh/undamaged post-mortem samples
• avoid leaving ectoparasites
– as long as the animal is alive, the ectoparasites are likely to stay present. ßà If you
trap an animal with a kill trap, then the parasites will leave and look for another host
• species protected or endangered
• non-target species can be released
• Ethical - welfare concerns
– capture stress
– temperature (e.g. in Tanzania: traps will be taken away before 9 am à we don’t want
the animals to be cooked ßà Belgium, in the winter, we will check every hour)
– food, water
– away from nest (mothers that need to lactate their pups à you don’t want to interfere
with the normal populaNon dynamics)
– removal from trap
• Ethical - welfare miNgaNons
– cover traps
– provide bedding, food
– limit Nme in trap
• Live traps – single capture
– ArNsanal wire mesh trap, Havahart trap, Sherman Light Folding Aluminium Trap,
TripTrap, arNsanal box trap, Longworth, Heslinga
• Live traps – mulNple capture
– Trap many more individuals (duh!)
– AddiNonal Ethical – welfare concerns
o intra/interspecific interacNons à if these are animals that don’t like each
other (one is the prey)
à can cause a lot of stress + species that normally live solitary, will fight in the
trap
o predaNon
o risk for drowning
