Dry-Land Nest-Site of a Western Grebe Colony

Nero, Robert W.; Lahrman, Fred W.; Bard, Fred G.

doi:10.2307/4081980

Cited by 13 publications

(5 citation statements)

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“…Complete nest failure occurred once (in 1999) when water level decreases, probably due to lake draw-down for local irrigation purposes, resulted in grebe nests on dry ground. It is unusual for Aechmophorus grebes to even attempt to nest on land and it has been reported only once (Nero et al 1958), as they are strongly dependent upon water level stability and stable emergent vegetation for nesting (Parmelee and Parmelee 1997). With 1999 removed from our analysis, grebe productivity and size of the nesting population improved/increased in the ''post-remediation'' period ( Fig.…”

Section: Fig 2 Adultmentioning

confidence: 92%

Mercury Residues and Productivity in Osprey and Grebes From a Mine‐dominated Ecosystem

Anderson

Suchanek

Eagles‐Smith

et al. 2008

Ecological Applications

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Grebe productivity at Clear Lake improved from ;0.1 to 0.5 fledged young per adult during the latter part of the study when human disturbance was prevented. At that period in time, improved productivity did not differ from our reference site at Eagle Lake. Human disturbance, however, as a co-factor made it impossible to evaluate statistically subtle Hg effects on grebe productivity at Clear Lake. Osprey reproduced sufficiently to maintain increasing breeding numbers from 1992 to 2006. Mercury in Clear Lake water, sediments, invertebrates, and fish did not decline from 1992 to 2003, but a shift in trophic structure induced by an introduced planktivorous fish species may have caused significant alterations in Hg concentrations in several species of prey fishes that may have produced concomitant changes in Osprey and grebe Hg exposure. The temporary declines observed in grebe and Osprey feather residues in the late 1990s, with coincidental improvements in reproductive performance, however, could not be attributed to remediation at the mine site.

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Section: Fig 2 Adultmentioning

confidence: 92%

Mercury Residues and Productivity in Osprey and Grebes From a Mine‐dominated Ecosystem

Anderson

Suchanek

Eagles‐Smith

et al. 2008

Ecological Applications

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“…Of possible significance in relation to the marked sexual dimorphism in the Western Grebe is the fact that this species is the most gregarious grebe, nesting colonially, often by the hundreds of pairs (Nero et al, 1958). Feeding by colony members occurs in a common area outside the small nesting territories, where, according to Lawrence (1950), the birds scatter, with at least 200 feet of open water between individuals.…”

Section: Several Other Examples Of Marked Sexual Dimorphism In Bill Smentioning

confidence: 99%

Sexual Dimorphism and Differential Niche Utilization in Birds

1966

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“…The proportions of marsh nests and open water nests at Clear Lake and associated wetlands varied greatly among colony sites and years, and were highly correlated with water level, with open water nests more prevalent during low water level. We never observed active dry-land nests described by others (Nero et al 1958, Nero 1959, Lindvall and Low 1982, Santolo 2021, although a few nests became stranded on dry land and were abandoned by the grebes as water level declined.…”

Section: Types Of Grebe Nestsmentioning

confidence: 46%

Historical and Recent Breeding of the Western Grebe and Clark's Grebe in a Severely Impaired Ecosystem at Clear Lake, California

Hayes

McIntosh²,

Turner

et al. 2022

Monographs of the Western North American Naturalist

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Clear Lake is a large (176.7-km 2 ) natural lake in northern California, USA. An estimated 1000 pairs of Western Grebes (Aechmophorus occidentalis) and Clark's Grebes (A. clarkii) nested on the lake prior to massive applications of the pesticide dichlorodiphenyldichloroethane (DDD) to kill the Clear Lake gnat (Chaoborus astictopus) during 1949-1957. Biomagnification of DDD was implicated as the cause of several mass mortality events of grebes and short-term reproductive failure in the 1950s, although other factors such as mercury (Hg) poisoning may have contributed. Successful nesting resumed in 1960 and increased gradually, with up to 165 nests in 1967 but fewer through 1976. Subsequent surveys revealed up to 390 nests annually during 1992-1995 and up to 2675 nests annually during 1996-2010. We conducted 7-29 nest surveys annually during 2010-2019 and found a mean of 3123 nests per year. The annual number of nests varied dramatically (range 898 to 5936) and was unrelated to water level. The grebes nested at 28 sites in Clear Lake and 9 sites in associated wetlands, with proportionately more nests on Clear Lake and fewer nests in adjacent wetlands during years with low water level. Western Grebes attended 84.9% of the nests and Clark's Grebes attended 15.1%. During years with low water, there were proportionately more open water nests, which were anchored to submergent vegetation farther from shore and in deeper water than marsh nests, which were more densely placed in emergent vegetation closer to shore in shallower water. Brood surveys along the perimeter of the lake at the end of each breeding season revealed considerable variation in the number of young (1-599, x -= 153.9), young per nest (0.00025-0.118, x -= 0.04), and productivity ratio of young to adults (0.0006-0.252, x -= 0.07). Reproductive success was unrelated to water level. Wind-generated waves were a major cause of nest failure, destroying up to 35% of a year's nests. Predation on eggs was also a major cause of nest failure. American Crow (Corvus brachyrhynchos) was the dominant predator during the day (84% of predation events), and northern raccoon (Procyon lotor) was the dominant predator at night (98% of predation events). Nocturnal predation by mammals occurred most frequently when water level was high because nests were placed closer to shore and were more accessible. The grebes' breeding population has recovered since DDD biomagnification during the 1950s and may be larger due to 2 introduced fish species competing for plankton with benthic larvae of the Clear Lake gnat, which previously transferred large quantities of biomass from aquatic to terrestrial ecosystems during emergence. However, the grebes' reproductive success remains lower at Clear Lake than at several other breeding localities. The bioaccumulation and biomagnification of toxic chemicals and the periodic reductions of prey fish from hypoxic areas of the lake during periods of intense cyanobacterial and algal blooms may reduce reproductive success.

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Dry-Land Nest-Site of a Western Grebe Colony

Cited by 13 publications

References 0 publications

Mercury Residues and Productivity in Osprey and Grebes From a Mine‐dominated Ecosystem

Mercury Residues and Productivity in Osprey and Grebes From a Mine‐dominated Ecosystem

Sexual Dimorphism and Differential Niche Utilization in Birds

Historical and Recent Breeding of the Western Grebe and Clark's Grebe in a Severely Impaired Ecosystem at Clear Lake, California

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