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BOBOLINK Scientific Name: Dolichonyx oryzivorus Species Code: B-BOBO Status: Blue-listed Distribution • Provincial Range In the summer the Bobolink occur in the Sub-Boreal Interior, Central Interior, Southern Interior Mountains, and Southern Interior Ecoprovinces. The Bobolink’s breeding distribution ranges from a narrow corridor of the southeastern Cariboo-Chilcotin, south to the southern Okanagan valley and east to the Kootenays (Vandamme 1995). • Elevational Range: Sea-Level to 1300m. • Provincial Context Bobolink numbers in British Columbia are declining probably due to loss of habitat. It is estimated that there are less than 500 birds in British Columbia (Vandamme 1995). • Project Area: Ecoprovince: Central Interior Ecoregions: Chilcotin Ranges and Fraser Plateau Ecosections: Central Chilcotin Ranges (CCR), Chilcotin Plateau (CHP) and Fraser River Basin (FRB) Biogeoclimatic Zones: BGxh3, BGxw2, IDFxm; IDFdk3; IDFdk4; MSxk; MSxv; ESSFxv2, ESSFxvp2; SBPSxc The ecosections and biogeoclimatic zones that have been italicized indicate areas within the project area, that have suitable habitat for the species under consideration, and have therefore been rated. Ecology and Key Habitat Requirements Bobolinks occur in tall grass, flooded meadows, dense pasture or alfalfa fields. During the growing season Bobolinks are mainly insectivorous and feed on caterpillars, grasshoppers and beetles and occasionally on grains and seeds (Vandamme 1995). The Bobolink responds positively to moderate grazing in tall grasslands and negatively to heavy grazing in shorter grasslands (Vandamme 1995). In British Columbia, the Bobolink appears to be dependent on artificially cultivated habitats and therefore much of its habitat is on privately owned land. Habitat Use and Life Requisites The life requisites that will be rated for Bobolink are: living and reproducing (eggs) which are described in detail below. • Living Crop damaging insects are the primary diet of Bobolinks during the growing season. They feed and seek cover in tall grass areas, flooded meadows, prairie, cultivated fields and alfalfa and clover fields (Vandamme 1995). • Reproducing Eggs are laid in June to July and hatch after an incubation period of 10-13 days (Vandamme 1995). Bobolinks breed in cultivated fields and moist meadows. Plant species that have been found common to breeding sites are poa sp., carex sp., horsetails, buttercups, daisies, red and white clover, thistle, dandelions, purple vetch and alfalfa (Vandamme 1995). Suitable breeding habitat can be found in the Bunchgrass, Ponderosa Pine, Interior Douglas-fir and Interior Cedar-Hemlock biogeoclimatic zones (Vandamme 1995). Seasons of Use Bobolink are a migratory species and are only in the study area for the growing season. The Living life requisite is required for the growing season and the Reproducing life requisite is only required for the breeding season. Table 1 summarizes the life requisites required for each month of the year. Table 1. Monthly Life Requisites for Bobolink. Life Requisite NA NA NA NA Living, Reproducing (eggs) Living, Reproducing (eggs) Living, Reproducing (eggs) Living NA NA NA NA Month January February March April May June July August September October November December Season Winter Winter Winter Winter Growing Growing Growing Growing Winter Winter Winter Winter Habitat Use and Ecosystem Attributes Table 2 outlines how each life requisite relates to specific ecosystem attributes (e.g., site series/ecosystem unit, plant species, canopy closure, age structure, slope, aspect, terrain characteristics). Table 2. Terrestrial Ecosystem Mapping (TEM) Relationships for each Life Requisite for Bobolink Life Requisite Living Habitat Reproducing Habitat (eggs) TEM Attribute - site: site disturbance, structural stage - soil/terrain: flooding regime - vegetation: % cover by layer, plant species - site: site disturbance, structural stage - soil/terrain: flooding regime - vegetation: % cover by layer, plant species Ratings There is an intermediate level of knowledge on the habitat requirements of Bobolink in British Columbia and thus, a 4-class rating scheme will be used. • Provincial Benchmark Ecosection: NOB Biogeoclimatic Zone: IDFdm, IDFdk or IDFxm Habitats: grasslands/cultivated fields • Ratings Assumptions 1. Cultivated hayfields and weedy pastures will be rated up to moderate for living and reproducing. 2. Moist grassland habitats will be rated up to low for living and reproducing. Table 3. Summary of habitat requirements for Bobolink in the study area. Season Growing Life Requisite Living (LI) Structural Stage 2 Growing Reproducing (RE) 2 Requirements Tall grass, flooded meadows, dense pasture or alfalfa fields. Tall grass, flooded meadows, dense pasture or alfalfa fields. • Ratings Adjustment Considerations Final capability and suitability map products may incorporate 1) landscape heterogeneity and connectivity; 2) habitats adjacent to significant anthropogenic disturbance regimes (e.g. settlements); 3) interspersion of different structural stages within the landscape. Please note that eventhough structural stage substage or modifiers and stand composition modifiers were employed in the original mapping, these units (other than structural stage modifier 3a and 3b) have not been included in the final ratings tables. This is because the ratings for the modified and unmodified ecosystem units are the same and including these units in the final ratings table would in turn make the ratings table too cumbersome. In instances where the modified ecosystem unit (either structural stage substage or modifiers and stand composition modifiers) is mapped, please use the wildlife habitat rating for the same unmodified ecosystem unit. References Vandamme, L.M. 1995. Status report on the Bobolink (Dolichonyx oryzivorus) in British Columbia. B.C. Environment, Wildlife Branch, Nelson, B.C. 16pp. Stevens, V. 1993. Wildlife Diversity in British Columbia: Distribution and Habitat Use in Biogeoclimatic Zones Draft Report. Wildlife Interpretations Subgroup. B.C. Ministry of Environment, Lands, and Parks. B.C. Ministry of Forests. Victoria B.C.