The energetic implications of precocial development for three shorebird species breeding in a warm environment

We investigated the effect of body size, parental behaviour and timing of breeding on the chick growth and energetics of three precocial shorebird (Charadrii) species in a warm sub-tropical environment: the Kittlitz's Plover Charadrius pecuarius , Blacksmith Lapwing Vanellus armatus , and Crowned Lapwing V. coronatus . The three species exhibited slower growth, longer pre-fledging periods and lower energy expenditure during the pre-fledging period than Arctic and temperate zone relatives of similar size. It was found that relative growth rates of charadriid and scolopacid species increased by 1.77% per degree latitude. Blacksmith and Crowned Lapwings are of similar size (i.e. about 160 g), about four times the mass of Kittlitz's Plovers. Taking body mass into account, the resting metabolic rate and daily energy expenditure of the three study species were similar. The relative amounts of energy needed for chicks to grow from a hatchling to a fledgling were low for the three species studied. The relative amount of energy needed to complete growth in charadriid and scolopacid species increased by 2.54% per degree latitude. Because Crowned Lapwings exhibited faster growth than Blacksmith Lapwings but similar daily energy expenditure we suggest that Blacksmith Lapwings compensate for greater energy expenditure in colder weather by growing more slowly. We suggest that small growth rate coefficient, low resting metabolic rate and low daily energy expenditure are adaptations to lower food availability and milder ambient temperatures in sub-tropical breeding habitats compared to temperate or Arctic regions.     

Two contemporaneous equilibrium communities in the Ordovician of Wisconsin

Two statistically different fossil assemblages were recognized in the Mifflin Submember of the Platteville Formation. These are believed to be ecologic communities because of their recurrence over a large area, their well-defined trophic structure, and their concurrence with lithofacies boundaries. The Hesperorthis—Eoleperditia community, which roughly coincides with the limestone facies of the Mifflin, has a diverse brachiopod fauna, abundant ostracodes, and several forms of trilobites and gastropods. The Hesperorthis-Sinuites community, coincident with the Miffin dolomite facies, contains abundant. but less diverse, brachiopods, and fewer trilobites and ostracodes. Gastropods and cephalopods are more abundant and diverse, and corals and bivalves are present. In both communities the most abundant genera were non-competitive in terms of trophic resources. and each trophic group was dominated by one or two genera. The two communities are interpreted to be equilibrium associations based on their vertical persistence through the section. Lithologic and faunal evidence indicates that these communities inhabited a quiet-water open-shelf environment which was occasionally disturbed by physical reworking (storm?) events. The distinction of two separate communities within an overall rather homogeneous environment suggests that the control was not physical energy or substrate type but a non-preservable factor such as food supply.