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Insectivory versus piscivory in Black Terns: Implications for food provisioning and growth of chicks

Waterbirds

By:
and
DOI: 10.1675/1524-4695(2005)28[436:IVPIBT]2.0.CO;2

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Abstract

The Black Tern (Chlidonias niger) is known for insectivory in their breeding range, but they are piscivorous in winter and feed some fish to chicks. Fish have potentially high value for chick provisioning because of their larger mass, but the relative value of fish and insect diets for chick growth is unknown. In 1999-2000, we documented use of fish and insects for provisioning chicks at four Black Tern colonies in Maine and examined chick growth rates at two colonies (Douglas Pond and Carlton Pond) that differed in fish and insect use. Deliveries of fish and insects to broods were documented using video cameras and observations from blinds, while concurrently measuring chick growth in nest enclosures. Fish use was substantial (>25% of deliveries) at three of four colonies. Fish comprised 29% of items and 56% of metabolizable energy delivered to chicks at Douglas Pond compared to 13% of items and 22% of metabolizeable energy at Carlton Pond. Food delivery rate was inversely related to the proportion of large fish. In brood diets at Douglas and Carlton Ponds and increased with brood age at Carlton Pond only, apparently due to high insect use. Chick growth rate did not vary with respect to fish and insect composition of diets. It is concluded that adults were able to raise chicks through age 12 d at comparable growth rates with insect-or fish-dominated diets. Use of fish may be more energy efficient for adults, and the capability to use both fish and insects may reduce potential variability in food availability during the breeding season.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Insectivory versus piscivory in Black Terns: Implications for food provisioning and growth of chicks
Series title:
Waterbirds
DOI:
10.1675/1524-4695(2005)28[436:IVPIBT]2.0.CO;2
Volume
28
Issue:
4
Year Published:
2005
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Waterbirds
First page:
436
Last page:
444
Number of Pages:
9