Marsh Flora Research Articles

Behavioral Interactions of Red-Winged Blackbirds and Common Grackles on a Common Breeding Ground

ECOLOGISTs have long been engaged in the study of relationships between species, but ethologists have all too often ignored interspecies relationships, with the result that the behavioral aspects of community ecology or competition are poorly known. The few recent detailed studies of interspecific behavior (Simmons, 1951; Rand, 1954; Lanyon, 1957; Selander and Giller, 1959, 1961; Moynihan, 1962, 1963; Orians and Collier, 1963; Orians and Willson, 1964) have exposed new approaches to investigations of ecological relationships (see Wynne-Edwards, 1962). This study was undertaken to examine the nature and effects of behavioral interactions between two icterids, the Red-winged Blackbird (Agelaius pkieniceus) and the Common Grackle (Quiscalus quiscula), in a situation where the two were breeding together in a small cattail marsh and were as a consequence potentially in competition. Red-wings nest in a wide range of habitats, but usually are closely associated with marshes and, indeed, are often the dominant species of the Nearctic marsh avifauna (Allen, 1914). Grackles, while being quite adaptable in their nesting habits and utilizing a wide range of nesting substrates (see Bent, 1958), apparently only sporadically nest in marshes. Indeed, Beecher (1942), in analyzing nesting substrates of several in relation to available edge growth, concluded that cattails were pessimum substrate for grackles and supra-optimum for Red-wings. Thus in a situation in which both utilize marsh flora for nesting substrate, any interpretation of the relationships between the must recognize that the habitat is typical for Red-wings and unusual for grackles.

Modern Pools and Carboniferous Analogies

The origin of coal is a difficult problem which is very far from being solved. The Coal Measure flora has long been extinct, and the modern representatives are feeble folk, almost crowded out of existence by plants of very different appearance and internal structure. The modern marsh flora is not primitive but secondary, and consists almost entirely of land plants which have taken to the water habitat again, just as the whale, porpoise, and seal are land animals which have gone back to rejoin their remote ancestral relatives in the sea. Homologous comparisons between past and present are therefore practically impossible, but some common pool developments of to-day may provide useful analogies if nothing more.