Main River Systems Research Articles

IMPROVEMENT OF TUSSOCK GRASSLANDS OF SOUTHLAND

The tussock grasslands of Southland play an important role in the agriculture of the province, both directly and indirectly. This paper aims therefore to focus some light on the improvement of the tussock grasslands in relation to run management and soil and water conservation. The area under discussion is in the northern Southland district and comprises the Eyre, Takitimo, GZvie, 'Thm-,- a& Livingston Mountains- The h& w+r catchments of the main river systems of Southland originate in this higher altitude tussock country, with the Aparima commencing in the Takitimos, the Oreti and Mataura in the Eyre, the Waikaia in the Garvies, and the Mararoa in the Thomson and Livingston Ranges.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA GREEN-WINGED TEAL

The migrations of the Pacific Coast population of Anas carolinensis parallel in time and space those of Anas acuta. Both use the same migration routes along the coast and along the main north and south river systems of the interior. So also both nest more commonly in Alaska than elsewhere. The peak of the spring migration usually is reached in late March or early April; the peak of the autumn migration usually is in late October and early November. A relatively large number normally winter on the Coastal Plain. Very few winter in the interior. Study of banding data reveals that (1) autumn transients through the Coastal Plain follow the coast route south to the mouth of the Columbia River and beyond through Oregon and California, rarely passing east of the High Sierras, (2) few individuals among the population following interior routes reach the coast, the tendency being to swing eastward to the Great Basin. The two main flyways through British Columbia, one on the coast the other through the interior, differ in at least one important respect, viz., along the interior route are many more or less isolated areas of suitable nesting grounds whereas on the coast there are none. A small nesting population, fluctuating annually in numbers, is widely distributed through the interior, the center of abundance being the Cariboo Parklands—the term abundance being used in a relative sense. Actually the population is small and dispersed. In the year 1938 a total of only 17 broods was counted on a study area of 60 sq. mi. containing a high average of highly productive waterfowl territory. Smaller counts were made here in each of the years following 1938. Egg-laying begins in May; there is some loss of early clutches through crow predation compensated for by later, and usually more successful, nesting. It is not unusual for females to be incubating a second clutch of eggs in early July. Nest sites are in dry places nearly always adjacent to a small pond or marsh in the grasslands. The earliest and latest dates for records of downy young are June 20 and Aug. 10. The average number of young in 48 broods counted in July, and 17 broods counted in August, was the same viz. 6.2. This high survival rate may be attributed in part to the spirited defense of young commonly practised by the female parent. Adult males in small number may associate on a common loafing place during the egg-laying period, and for a week or so after incubation has started. Later they retreat to marsh habitat and begin the yearly molt. Full eclipse of the body plumage usually is attained prior to renewal of the flight feathers. The molt from eclipse to nuptial dress is not completed until late October. The first adult plumage of young males is not fully attained until January. The sex ratio appears to maintain a not unfavorable biological balance—a total of 4264 banded green-winged teal was composed of 2225 males and 2039 females. The food range of the species is not extensive. Seeds, chiefly those of aquatic plants, were present in the stomachs of all 69 adults examined, and in many constituted the bulk of food eaten. Insects are second, miscellaneous animals third, in importance. The green-winged teal is a valuable game species; none of its habits is detrimental to agricultural or other human interests.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA: PINTAIL

Dafila acuta is an abundant transient through British Columbia following routes along the outer coast, the inner coast, and the main north and south river systems of the interior. The spring migration takes place during March and April and is not protracted but the autumn migration is one of successive movements from mid-August to early December. The largest flight sometimes appears on the mainland coast in late October. Both northbound and southbound flocks concentrate on the Coastal Plain. The chief wintering grounds are in western Oregon and in California, the most densely populated nesting grounds in Alaska. Recoveries of banded birds have verified observational migration data and have shown also that many individuals use the same route in successive years, some arriving at a given point on approximately the same date. In British Columbia the principal nesting ground is the parklands of the Cariboo region and the peak of the spring migration is in late March or early April. Following its conclusion the residual population is scattered over a wide area characterized by grassland and many types of ponds and sloughs. Courtship is at its height in April and laying commences in May. Nest sites usually are dry and may be several hundred yards from the nearest water. The majority of young appear in June and are led by the females to meadows and marshes provided with adequate cover. The females remain with the brood and actively defend them during adolescence. Males leave the females when incubation begins and gather in small bands on water adjacent to the nesting grounds. Many migrate in advance of the flightless period. Downy young feed largely on the larvae of aquatic insects. The most important item in the diet of adults during autumn and winter is seeds of various meadow and aquatic plants. On the coast this element is characterized by Polygonaceae and Scirpus americanus, in the interior by Potamogetons and Scirpus acutus. Insects and animal matter generally constitute a less important food. The pintail is second to the mallard, Anas platyrhynchos, in economic importance and like it is a source of revenue to the Province. On the debit side the pintail causes some loss to agriculture by eating forage crops but this is not extensive and is amenable to control.

STUDIES OF WATERFOWL IN BRITISH COLUMBIA: MALLARD

Anas platyrhynchos is widely distributed along the Pacific coast. The main winter range extends from coastal Alaska to northern California with the greatest concentration in the lower Fraser Valley of British Columbia and adjacent counties in Washington State. To this coastal plain come summer populations from interior British Columbia, Alberta, Yukon Territory, and Alaska. Here also is a relatively small resident population. A winter population in the interior is increasing in numbers. Migration routes follow the coast and the main river systems, the latter leading to a wide highway of dispersal along the interior plateaux. Band recoveries identify these migration highways and the seasonal movements; they show that mallards follow the same general routes, return in successive years to the same wintering grounds and that population units remain together. On the southern coast nesting commences early and downy young have been seen in March and April. In the interior the majority nest in May and many different types of nesting habitats are occupied. Males leave the females after incubation has started and by early June many, still in full breeding plumage, have gathered in flocks. Subsequently as males start to eclipse they become less gregarious. When the flight feathers are renewed the males again assemble in flocks that later are joined by females and flying young. On the coast one winter population feeds chiefly on seeds and vegetation, secured on flooded fields; another feeds exclusively on salmon eggs and salmon flesh; a third, occupying the littoral, on algae and small marine animals. In the interior the seeds of aquatic plants, more particularly Scirpus acutus and Potamogeton pectinatus are important foods, so are aquatic insects chiefly Odonata nymphs and corixids. One population in autumn lives almost entirely on grain secured from the fields. The mallard is the duck species of greatest economic importance in British Columbia and the source of a considerable item of revenue to the province. This value is believed to outweigh an economic loss of undetermined proportion brought about by the mallards' consumption of salmon eggs and damage to agricultural crops.