A SYNOPSIS OF THE PESTICIDE PROBLEM
83
laboratory animal. Only very broad conclusions can be drawn from such
assumptions because organisms react very differently to the same
pesticide, see page 94 and Table 111.
One of the most valuable by-products of the pesticide controversy
is that it has shown how very few elementary ecological data are
available, even in Britain where the flora and fauna have been more
thoroughly studied than in most countries. In this country only the
distribution of flowering plants has been systematically studied and
recorded (Perring and Walters, 1962). Until recently the distribution
of lower plants, vertebrates and the more conspicuous invertebrates
has not even been studied systematically. For most animal species
even crude distribution maps could not be drawn.
Except for a very few species of birds no attempt has been made to
assess population numbers, but even in this group which provides more
scope for census work than any other, population data are largely
lacking: of the 200 or so species of breeding birds in Britain, population
estimates based on total censuses or censuses of extensive sample areas
have only been made for fifteen species. In only four have population
estimates been made in three or more years and in only two of three
were the first censuses made before the large scale introduction of
pesticides (Moore, 1965b). Therefore there is extremely little systematic
knowledge about population fluctuations in the past, and so much
discussion on the effects of pesticides rests on a posteriori arguments.
Man is the only species for which population data are adequate.
Many animals ingest pesticides through their food, therefore knowledge about their feeding habits is essential in assessing the effects of
pesticides upon them. Lists of recorded foods are available for a number
of organisms, mainly birds and the larvae of Lepidoptera. Enough is
known to show that most animals ar0 not specific in their choice of
food but are to a greater or lesser extent opportunists within varying
limits. This is not to say that some species do not have preferences or
that some do not show distinct patterns. For example several herbivorous birds initially feed their young on insects. In a few cases feeding
patterns of local populations have been studied systematically, for
example, the Tawny Owls of Wytham Wood by Southern (1954).
But for large populations of species which feed on several types of food,
statistical information about the proportions of different types eaten
is not available. Again we lack essential basic data. I n assessing the
effects of a pesticide on a species, data on populations, residues, toxicology and feeding habits are required. A list of vertebrate species
recently or currently being studied in Britain in ordex to determine the
effects of organochlorine insecticides is given in Table I. A reasonable
amount is known about the feeding habits of all these species. It will
83
laboratory animal. Only very broad conclusions can be drawn from such
assumptions because organisms react very differently to the same
pesticide, see page 94 and Table 111.
One of the most valuable by-products of the pesticide controversy
is that it has shown how very few elementary ecological data are
available, even in Britain where the flora and fauna have been more
thoroughly studied than in most countries. In this country only the
distribution of flowering plants has been systematically studied and
recorded (Perring and Walters, 1962). Until recently the distribution
of lower plants, vertebrates and the more conspicuous invertebrates
has not even been studied systematically. For most animal species
even crude distribution maps could not be drawn.
Except for a very few species of birds no attempt has been made to
assess population numbers, but even in this group which provides more
scope for census work than any other, population data are largely
lacking: of the 200 or so species of breeding birds in Britain, population
estimates based on total censuses or censuses of extensive sample areas
have only been made for fifteen species. In only four have population
estimates been made in three or more years and in only two of three
were the first censuses made before the large scale introduction of
pesticides (Moore, 1965b). Therefore there is extremely little systematic
knowledge about population fluctuations in the past, and so much
discussion on the effects of pesticides rests on a posteriori arguments.
Man is the only species for which population data are adequate.
Many animals ingest pesticides through their food, therefore knowledge about their feeding habits is essential in assessing the effects of
pesticides upon them. Lists of recorded foods are available for a number
of organisms, mainly birds and the larvae of Lepidoptera. Enough is
known to show that most animals ar0 not specific in their choice of
food but are to a greater or lesser extent opportunists within varying
limits. This is not to say that some species do not have preferences or
that some do not show distinct patterns. For example several herbivorous birds initially feed their young on insects. In a few cases feeding
patterns of local populations have been studied systematically, for
example, the Tawny Owls of Wytham Wood by Southern (1954).
But for large populations of species which feed on several types of food,
statistical information about the proportions of different types eaten
is not available. Again we lack essential basic data. I n assessing the
effects of a pesticide on a species, data on populations, residues, toxicology and feeding habits are required. A list of vertebrate species
recently or currently being studied in Britain in ordex to determine the
effects of organochlorine insecticides is given in Table I. A reasonable
amount is known about the feeding habits of all these species. It will