Boat-tailed Grackle (Quiscalus major)

Abstract We studied the effects of nutrient enrichment on the bird community in an oligotrophic wetland, the Florida Everglades. Among the non-wading birds surveyed in 1996 and 1997, Boat-tailed Grackles (Quiscalus major) and Common Moorhens (Gallinula chloropus) were consistently more abundant in enriched sites, whereas Common Yellowthroats (Geothlypis trichas) were consistently more abundant in unenriched sites. The abundance of Red-winged Blackbird (Agelaius phoeniceus) was not significantly different between enriched and unenriched sites. Among wading birds, Wood Storks (Mycteria americana) and Great Egrets (Ardea alba) were significantly more abundant in enriched than unenriched areas in a dry year, 1991. Great Egrets and all wading species combined were significantly more abundant in enriched than unenriched areas in the wet year, 1995. Great Blue Herons (Ardea herodias) and White Ibises (Eudocimus albus) did not differ in abundance between enriched and unenriched areas in the dry or wet year. A significant interaction between water depth and nutrient status in the wet year indicated that wading bird abundance increased with water depth only in nutrient-enriched areas presumably because the enriched areas had greater food availability than unenriched areas at the same water depth. Bird abundance appeared to increase in nutrient-enriched areas; however, this increase was accompanied by a shift in species composition typically found in the unenriched Everglades and was a fundamental change in the Everglades' distinctive structure. Respuestas de las Aves al Enriquecimiento con Nutrientes en un Humedal Oligotrófico, en los Pantanos de los Everglades en Florida Resumen. Estudiamos los efectos del enriquecimiento con nutrientes sobre la comunidad de aves en un humedal oligotrófico, los pantanos de los Everglades en Florida. Entre las aves no vadeadoras censadas en 1996 y 1997, Quiscalus major y Gallinula chloropus fueron consistentemente más abundantes en sitios enriquecidos, mientras que Geothlypis trichas fue consistentemente más abundante en sitios no enriquecidos. La abundancia de Agelaius phoeniceus no difirió significativamente entre los sitios enriquecidos y no enriquecidos. Entre las aves vadeadoras, Mycteria americana y Ardea alba fueron significativamente más abundantes en áreas enriquecidas que en las no enriquecidas durante 1991, un año seco. En 1995, un año húmedo, Ardea alba y todas las demás aves vadeadoras fueron significativamente más abundantes en áreas enriquecidas que en las no enriquecidas. Ardea herodias y Eudocimus albus no difirieron en abundancia entre áreas enriquecidas y no enriquecidas en el año húmedo ni en el año seco. En el año húmedo, encontramos una interacción significativa entre la profundidad del agua y el estado de los nutrientes, lo que indicó que la abundancia de aves vadeadoras aumentó sólo en las áreas enriquecidas con nutrientes, presumiblemente debido a que las áreas enriquecidas presentaron mayor disponibilidad de alimento que las áreas no enriquecidas de una profundidad de agua equivalente. La abundancia de aves pareció aumentar en las áreas enriquecidas con nutrientes; sin embargo, este incremento estuvo acompañado con un cambio en la composición de las especies encontradas normalmente en los pantanos de los Everglades de Florida que no han sido enriquecidos, y representó un cambio fundamental en la estructura característica de los Everglades.

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BLOOD GAS, LACTATE, AND HEMATOLOGY EFFECTS OF VENIPUNCTURE TIMING AND LOCATION AFTER MIST-NET CAPTURE OF MOURNING DOVES (ZENAIDA MACROURA), BOAT-TAILED GRACKLES (QUISCALUS MAJOR), AND HOUSE SPARROWS (PASSER DOMESTICUS)

Journal of Wildlife Diseases ◽

10.7589/jwdi-52-01s1-06.1 ◽

2015 ◽

Author(s):

Craig A. Harms ◽

Maggie R. Jinks ◽

Ronald V. Harms

Keyword(s):

Passer Domesticus ◽

Blood Gas ◽

House Sparrows ◽

Zenaida Macroura ◽

Mourning Doves ◽

Quiscalus Major ◽

Mist Net

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Nesting Success and Mortality of the Boat-Tailed Grackle

The Auk ◽

10.1093/auk/103.1.86 ◽

1986 ◽

Vol 103 (1) ◽

pp. 86-99 ◽

Cited By ~ 9

Author(s):

G. Thomas Bancroft

Keyword(s):

Success Rate ◽

Nest Survival ◽

Nesting Success ◽

Common Source ◽

Nesting Biology ◽

Individual Survival ◽

Nestling Survival ◽

Almost All ◽

Quiscalus Major ◽

Nestling Mortality

Abstract Of 605 Boat-tailed Grackle (Quiscalus major) nests with complete clutches, 60.5% fledged young. Survival of nests to the hatching stage averaged 78.7%, and survival from hatching to fledging averaged 76.9%. Nesting success between localities varied from none to almost all nests fledging some young. Fledging success for 3-egg clutches averaged 64.8% and was significantly higher than the 50.8% success rate that 2-egg clutches averaged. Individual survival of eggs from laying through hatching was lower in 2-egg clutches than in 3-egg clutches, but from hatching to fledging nestling survival was higher. Thus, in contrast to nest survival, equal proportions of eggs in 2- and 3-egg clutches produced fledglings. Predation was the greatest source of mortality, with predators taking 14.8% of the 1,605 eggs and 13.1% of the 1,145 nestlings. Of eggs that survived to the hatching stage, 9.2% failed to hatch. Starvation (13.4%) was the most common source of nestling mortality. Nest abandonment accounted for the death of 5.7% of the eggs and 2.9% of the young. The sources of mortality varied spatially and temporally in an unpredictable way. This uncertainty has resulted in the flexible nesting biology of grackles.

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