Sorry for the long and involved codes attached but these are the applicable codes. The short answer to your question, "Can my neighbor trap cats", is YES. If your cats stray onto the neighbors yard, they are subject to impoundment by the local authorities (whose responsibilities are listed below) and you are subject to fines and costs. As long as the neighbor turns the animal over to the animal control division and does not do away with it in some diabolical manner, they are within their legal rights to remove unwanted visitors in a humane fashion. Collars, tags, and a microchip are all effective tools to identify your pet but from reading the MC Sheriff's website, don't expect a call even if Fluffy is wearing tags. My suggestion, Fluffy is gone for 2 days, check the shelter and CALL immediately.
These are from the California state statutes and penal codes.
----------------------------------------------------------------31752. (a) The required holding period for a stray cat impounded
pursuant to this division shall be six business days, not including
the day of impoundment, except as follows:
(1) If the public or private shelter has made the cat available
for owner redemption on one weekday evening until at least 7:00 p.m.
or one weekend day, the holding period shall be four business days,
not including the day of impoundment.
(2) If the public or private shelter has fewer than three
full-time employees or is not open during all regular weekday
business hours, and if it has established a procedure to enable
owners to reclaim their cats by appointment at a mutually agreeable
time when the public or private shelter would otherwise be closed,
the holding period shall be four business days, not including the day
of impoundment.
Except as provided in Sections 17006 and 31752.5, stray cats shall
be held for owner redemption during the first three days of the
holding period, not including the day of impoundment, and shall be
available for owner redemption or adoption for the remainder of the
holding period.
(b) Except as provided in Section 17006, any stray cat that is
impounded pursuant to this division shall, prior to the euthanasia of
that animal, be released to a nonprofit, as defined in Section 501
(c)(3) of the Internal Revenue Code, animal rescue or adoption
organization if requested by the organization prior to the scheduled
euthanasia of that animal. In addition to any required spay or
neuter deposit, the public or private shelter, at its discretion, may
assess a fee, not to exceed the standard adoption fee, for animals
adopted or released. The public or private shelter may enter into
cooperative agreements with any animal rescue or adoption
organization.
(c) During the holding period required by this section and prior
to the adoption or euthanasia of a cat impounded pursuant to this
division, a public or private shelter shall scan the cat for a
microchip that identifies the owner of that cat and shall make
reasonable efforts to contact the owner and notify him or her that
his or her cat is impounded and is available for redemption.
31752.2. (a) Upon relinquishment of a cat to a public or private
shelter, the owner of that cat shall present sufficient
identification to establish his or her ownership of the cat and shall
sign a statement that he or she is the lawful owner of the cat.
(b) Any person who provides false information pursuant to this
subdivision about his or her ownership of the cat shall be liable to
the true owner of the cat in the amount of one thousand dollars
($1,000).
31752.5. (a) The Legislature finds and declares the following:
(1) Domestic cats' temperaments range from completely docile
indoor pets to completely unsocialized outdoor cats that avoid all
contact with humans.
(2) "Feral cats" are cats with temperaments that are completely
unsocialized, although frightened or injured tame pet cats may appear
to be feral.
(3) Some people care for or own feral cats.
(4) Feral cats pose particular safety hazards for shelter
employees.
(5) It is cruel to keep feral cats caged for long periods of time;
however, it is not always easy to distinguish a feral cat from a
frightened tame cat.
(b) For the purposes of this section, a "feral cat" is defined as
a cat without owner identification of any kind whose usual and
consistent temperament is extreme fear and resistance to contact with
people. A feral cat is totally unsocialized to people.
(c) Notwithstanding Section 31752, if an apparently feral cat has
not been reclaimed by its owner or caretaker within the first three
days of the required holding period, shelter personnel qualified to
verify the temperament of the animal shall verify whether it is feral
or tame by using a standardized protocol. If the cat is determined
to be docile or a frightened or difficult tame cat, the cat shall be
held for the entire required holding period specified in Section
31752. If the cat is determined to be truly feral, the cat may be
euthanized or relinquished to a nonprofit, as defined in Section 501
(c)(3) of the Internal Revenue Code, animal adoption organization
that agrees to the spaying or neutering of the cat if it has not
already been spayed or neutered. In addition to any required spay or
neuter deposit, the pound or shelter, at its discretion, may assess
a fee, not to exceed the standard adoption fee, for the animal
released.
597f. (a) Every owner, driver, or possessor of any animal, who
permits the animal to be in any building, enclosure, lane, street,
square, or lot, of any city, city and county, or judicial district,
without proper care and attention, shall, on conviction, be deemed
guilty of a misdemeanor. And it shall be the duty of any peace
officer, officer of the humane society, or officer of a pound or
animal regulation department of a public agency, to take possession
of the animal so abandoned or neglected and care for the animal until
it is redeemed by the owner or claimant, and the cost of caring for
the animal shall be a lien on the animal until the charges are paid.
Every sick, disabled, infirm, or crippled animal, except a dog or
cat, which shall be abandoned in any city, city and county, or
judicial district, may, if after due search no owner can be found
therefor, be killed by the officer; and it shall be the duty of all
peace officers, an officer of such society, or officer of a pound or
animal regulation department of a public agency to cause the animal
to be killed on information of such abandonment. The officer may
likewise take charge of any animal, including a dog or cat, that by
reason of lameness, sickness, feebleness, or neglect, is unfit for
the labor it is performing, or that in any other manner is being
cruelly treated; and, if the animal is not then in the custody of its
owner, the officer shall give notice thereof to the owner, if known,
and may provide suitable care for the animal until it is deemed to
be in a suitable condition to be delivered to the owner, and any
necessary expenses which may be incurred for taking care of and
keeping the animal shall be a lien thereon, to be paid before the
animal can be lawfully recovered.
(b) It shall be the duty of all officers of pounds or humane
societies, and animal regulation departments of public agencies to
convey, and for police and sheriff departments, to cause to be
conveyed all injured cats and dogs found without their owners in a
public place directly to a veterinarian known by the officer or
agency to be a veterinarian that ordinarily treats dogs and cats for
a determination of whether the animal shall be immediately and
humanely destroyed or shall be hospitalized under proper care and
given emergency treatment.
If the owner does not redeem the animal within the locally
prescribed waiting period, the veterinarian may personally perform
euthanasia on the animal; or, if the animal is treated and recovers
from its injuries, the veterinarian may keep the animal for purposes
of adoption, provided the responsible animal control agency has first
been contacted and has refused to take possession of the animal.
Whenever any animal is transferred pursuant to this subdivision to
a veterinarian in a clinic, such as an emergency clinic which is not
in continuous operation, the veterinarian may, in turn, transfer the
animal to an appropriate facility.
If the veterinarian determines that the animal shall be
hospitalized under proper care and given emergency treatment, the
costs of any services which are provided pending the owner's inquiry
to the agency, department, or society shall be paid from the dog
license fees, fines, and fees for impounding dogs in the city,
county, or city and county in which the animal was licensed or if the
animal is unlicensed the jurisdiction in which the animal was found,
subject to the provision that this cost be repaid by the animal's
owner. No veterinarian shall be criminally or civilly liable for any
decision which he or she makes or services which he or she provides
pursuant to this section.
(c) An animal control agency which takes possession of an animal
pursuant to subdivision (b), shall keep records of the whereabouts of
the animal for a 72-hour period from the time of possession and
those records shall be available to inspection by the public upon
request.
(d) Notwithstanding any other provisions of this section, any
officer of a pound or animal regulation department or humane society,
or any officer of a police or sheriff's department may, with the
approval of his or her immediate superior, humanely destroy any
abandoned animal in the field in any case where the animal is too
severely injured to move or where a veterinarian is not available and
it would be more humane to dispose of the animal