Diets of Pipits and Skylarks at Huiarua Station, Tokomaru Bay, North Island, New Zealand
- Zoology Department, Victoria University, Wellington, New Zealand
- Present address: Wildlife Service, Department of Internal Affairs, Private Bag, Wellington, New Zealand
The gizzard contents of 57 pipits and 64 skylarks collected from December 1973 to April 1976 at Huiarua Station, Tokomaru Bay are described.
Pipits fed mostly on invertebrates; in only nine percent of the gizzards did the volume of seeds exceed that of invertebrates. Adult Coleoptera, Hymenoptera and Diptera occurred in 77%, 67% and 63% of the gizzards respectively while adult insects of three other orders, insect larvae, insect pupae, Arachnida and seeds of four plant families were each recorded less frequently but in 10% or more of the gizzards gizzards. Only Diptera displayed significant seasonal variation in frequency of occurrence.
Skylarks ate mostly seeds; only 25 % of the gizzards contained a volume of invertebrates equal to or exceeding that of seeds. Seeds of Gramineae occurred more frequently than those of any other plant family (in 73% of the skylark gizzards) and adult Coleoptera were the most frequent invertebrates (66%). Seeds of eight other plant families, adult insects of two other orders, insect larvae, insect pupae and Arachnida were each recorded in 10% or more of the gizzards. Seasonally, only Coleoptera were taken with significantly variable frequency.
In addition to the difference in the relative importance volumetrically of invertebrates and seeds in each diet, significant differences were determined between pipits and skylarks in the occurrence of all the food groups most frequently consumed by each and it is concluded that the level of interspecific competition for food can not be regarded as high.