DETERMINATE AND INDETERMINATE EGG-LAYING PATTERNS - A REVIEW

Patterns of egg laying were recorded for 104 bird species by surveying the literature for experiments that involved removal or addition of conspecific eggs during laying. Although results were presented for all 104 species, data were considered sufficient to reliably determine laying type for only 46 species. Of the 46 species, 24 were determinate layers; they did not lay extra eggs in response to egg removal or did not curtail laying in response to egg addition. Twenty-two species were indeterminate layers. Three types of indeterminate laying were revealed: removal indeterminacy, in which birds responded to egg removal by laying extra eggs; addition indeterminacy, in which birds responded to egg addition by laying fewer than normal host eggs; and removal-and-addition indeterminacy, in which birds responded to egg removal by laying more eggs than normal and to egg addition by laying fewer eggs than normal. The frequency of indeterminacy increased with clutch size: none of the three species with single-egg clutches were indeterminate, 15 of the 32 species (47%) with average clutches of 2-8 eggs were indeterminate, and 7 of 11 species (64%) with average clutches of more than eight eggs were indeterminate. No differences were found in the frequency of laying types between birds with precocial and altricial young. The timing of egg removal and addition affected the experimental results; manipulations should be done early in laying in order to effectively evaluate laying pattern. Finally, I suggest a protocol for futher experiments designed to examine laying type.