Scientific policy and hybrid management

John R. Grehan jrg13 at PSU.EDU
Wed Jun 20 10:57:24 CDT 2001

The following is a cross posting from aliens-l at regarding
the role of science in environmental management for hybrids. It
specifically concerns the problematic nature of the New Zealand Department
of Conservation which has failed to establish a science policy to address
management issues concerning hybrid such as 'Tobin.' I have posted it here
as species concerns are likely of interest to members of Taxacom (although
the Tobin issue has been posted on Taxacom in the past).

Scientific policy and protocols for dealing with hybrid management

The question of hybrids being killed as part of a conservation program may
seem to be far removed from the concerns of those involved with the
management and control of 'alien' organisms since the former issue is about
the 'native' species while the latter issue is about 'introduced'
organisms. Yet beyond this distinction there are overlapping issues
concerning the need for carefully thought out policies or actions that have
identified a scientific justification for the procedures to be implemented.
Without scientific justification and associated policy it seems to me the
only defense available for management is little better than 'we felt like it.'

Philosophical criteria enter into all the scientific and management
decisions that are made every day in the conservation and management of our
environment, whether dealing with endangered species or the
not-so-endangered invasives. Paula Warren has suggested the case of the
execution of the black robin-Chatham Island tit hybrid (not with the tomtit
she referred to) is not so 'bizarre' as it was a 'natural' extension of a
particular need identified by managers. I contend that the decision was
bizarre in that it was carried out by a major scientific organization that
includes an entire department devoted to conservation science and yet this
organization failed to prepare a scientifically based policy to address the
possibility of a hybrid appearing, and once a hybrid did appear there was
no further development of a scientific policy to address the perceived

Neither the New Zealand Department of Conservation nor government cabinet
ministers for conservation have expressed any concern about this lack of a
science policy. Paula Warren even points out that a science policy for
hybrids is not a priority for the Department of Conservation. As a
scientist interested in environmental management, I find the lack of a
scientific foundation for management of hybrids deeply troubling.

For those not familiar with the New Zealand black robin-Chatham Island tit
hybrid situation I will recount the main features. The black robins were
considered to be in danger of extinction and their reproductive output was
increased by fostering black robin eggs with Chatham Island tits. When one
of these offspring was behaviorally imprinted as a tit, it proceeded to
mate with a tit and the result was a hybrid that was named "Tobin". Tobin
was declared persona non grata, photographed, and shot. A post hoc
justification was that it was a "freak biological event" and was a threat
to the genetic purity of the parent species. There appears to be no public
information as to who decided on the execution, or who carried the sentence
out and under what scientific oversight the procedure took place. The
"freak biological event" has since occurred at least three more times.

A discussion paper by the Threatened Species Unit of the Department of
Conservation simply noted (without scientific discussion or evaluation)
that the young hybrids should be removed because of their "potential to
damage this small and vulnerable population." The nature of this 'damage'
was never specified, and neither was there an explanation for the killing
being the necessary method of 'removal'. In 1994 the Minister of
Conservation was given another explanation  that destruction was needed
because the hybrid was a consequence of human intervention and so it was
appropriate for conservation managers to "correct" the problem. In 1998 I
was informed by DoC that Tobin was "destroyed by birdshot because the risk
to her evading capture to breed in later seasons was considered too great."
This justification represents a puzzle since the bird was sufficiently
accessible for a hand-held photo (later published) only some days earlier.
It appears that Tobin's status was considered sufficiently benign to allow
its release back into the wild, whereupon the situation was then deemed so
critical that birdshot was the only solution. Later hybrids were 'removed'
by .22 caliber bullets.

I was informed in 1996 that DoC decisions are "currently based on a
collective philosophy among threatened species management and that a policy
of a minimal interference with natural evolutionary process should be
followed during species transfers." No scientific clarification was
provided for either "collective philosophy" or "natural evolutionary
processes," or how these were applied for Tobin and her relatives.

The question of science policy and hybrid management is of general
significance not only for endangered species management, but also invasive
species management. What should happen if a species is introduced by humans
or by other (so called 'natural') agencies and hybridizes with a local
endemic species?

I would be very interested to hear from the list how other government
agencies and non-governmental organizations have documented scientifically
based protocols and procedures. If any are published I would be very
grateful for the citations. For unpublished documentation I would be
grateful to either receive copies or information on how I can request

For those more interested in these matters the Tobin saga is published in
the following book:

Craw, R. C., Heads, M. J., Grehan, J. R. 1999. Panbiogeography: tracking
the history of life. Oxford University Press, New York.

John Grehan

John Grehan
Frost Entomological Museum
Pennsylvania State University
Department of Entomology
501 ASI Building
University Park, PA 16802. USA.

Phone: (814) 863-2865
Fax: (814) 865-3048

Frost Museum

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