Common Raven Activity in Relation to Land use in Western Wyoming: Implications for Greater Sage-Grouse Reproductive Success

AbstractPrevious investigations using continuous video monitoring of greater sage-grouse Centrocercus urophasianus nests have unambiguously identified common ravens Corvus corax as an important egg predator within the western United States. The quantity of greater sage-grouse eggs an individual common raven consumes during the nesting period and the extent to which common ravens actively hunt greater sage-grouse nests are largely unknown. However, some evidence suggests that territorial breeding common ravens, rather than nonbreeding transients, are most likely responsible for nest depredations. We describe greater sage-grouse egg depredation observations obtained opportunistically from three common raven nests located in Idaho and Nevada where depredated greater sage-grouse eggs were found at or in the immediate vicinity of the nest site, including the caching of eggs in nearby rock crevices. We opportunistically monitored these nests by counting and removing depredated eggs and shell fragments from the nest sites during each visit to determine the extent to which the common raven pairs preyed on greater sage-grouse eggs. To our knowledge, our observations represent the first evidence that breeding, territorial pairs of common ravens cache greater sage-grouse eggs and are capable of depredating multiple greater sage-grouse nests.

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Influence of Habitat and Food Resource Availability on Common Raven Nest Site Selection and Reproductive Success in Mediterranean Forests

Birds ◽

10.3390/birds2030022 ◽

2021 ◽

Vol 2 (3) ◽

pp. 302-313

Author(s):

Amalia Segura ◽

Pelayo Acevedo

Keyword(s):

Reproductive Success ◽

Site Selection ◽

Habitat Structure ◽

Nest Site ◽

Food Resource ◽

Nest Site Selection ◽

High Density ◽

Mediterranean Forests ◽

Breeding Behavior ◽

Common Raven

Bird nest selection in forests can be influenced by the composition of key structural elements and resources. This has important consequences in terms of species population dynamics since it can determine reproduction success. Here, we assessed Common raven nest-site selection and reproductive success, and how these might be determined by foraging behavior and habitat structure. A previously documented breeding raven population that exerts high predation pressure on young Spur-thighed tortoises (Testudo graeca) in a Mediterranean forest was monitored. Generalized linear mixed models were performed to determine the singularities of the trees with nests and the drivers of reproductive success of breeding pairs of ravens. The results showed a high density of breeding pairs in the study area (0.8 pairs/km2), which selected taller trees in areas with higher bare ground cover and a high density of tortoises for nesting. Nests were spatially aggregated; breeding pairs occupied smaller territories and intraspecific competition seemed relaxed, reflecting the abundance of food resources. Most breeding pairs occasionally predated on young tortoises. Tortoises seem to play a part in raven reproductive success in our study area, which might be associated with the availability/catchability of young tortoises. The study illustrates that Spur-thighed tortoise distribution and abundance plays a role in the breeding behavior of ravens and is mediated by habitat structure. Understanding the drivers of nest-site selection and the breeding behavior of ravens is pivotal to implementing appropriate habitat management and conservation strategies across their distribution range, particularly in areas where ravens potentially affect threatened species.

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Lower bumblebee colony reproductive success in agricultural compared with urban environments

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.0807 ◽

2018 ◽

Vol 285 (1881) ◽

pp. 20180807 ◽

Cited By ~ 28

Author(s):

Ash E. Samuelson ◽

Richard J. Gill ◽

Mark J. F. Brown ◽

Ellouise Leadbeater

Keyword(s):

Land Use ◽

Reproductive Success ◽

Urban Areas ◽

Agricultural Landscape ◽

Agricultural Land ◽

Bombus Terrestris ◽

Strong Predictor ◽

Urban Land ◽

Urban Land Use ◽

Sexual Offspring

Urbanization represents a rapidly growing driver of land-use change. While it is clear that urbanization impacts species abundance and diversity, direct effects of urban land use on animal reproductive success are rarely documented. Here, we show that urban land use is linked to long-term colony reproductive output in a key pollinator. We reared colonies from wild-caught bumblebee ( Bombus terrestris ) queens, placed them at sites characterized by varying degrees of urbanization from inner city to rural farmland and monitored the production of sexual offspring across the entire colony cycle . Our land-use cluster analysis identified three site categories, and this categorization was a strong predictor of colony performance. Crucially, colonies in the two clusters characterized by urban development produced more sexual offspring than those in the cluster dominated by agricultural land. These colonies also reached higher peak size, had more food stores, encountered fewer parasite invasions and survived for longer. Our results show a link between urbanization and bumblebee colony reproductive success, supporting the theory that urban areas provide a refuge for pollinator populations in an otherwise barren agricultural landscape.

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Declining reproductive output in capercaillie and black grouse – 16 countries and 80 years

Animal Biology ◽

10.1163/15707563-00002514 ◽

2016 ◽

Vol 66 (3-4) ◽

pp. 363-400 ◽

Cited By ~ 14

Author(s):

Torfinn Jahren ◽

Torstein Storaas ◽

Tomas Willebrand ◽

Pål Fossland Moa ◽

Bjørn-Roar Hagen

Keyword(s):

Land Use ◽

Reproductive Success ◽

Boreal Forests ◽

Reproductive Output ◽

Temporal Trends ◽

Adult Survival ◽

Generalist Predator ◽

Black Grouse ◽

Proximate Cause ◽

Underlying Mechanisms

Declines in populations of capercaillie (Tetrao urogallus) and black grouse (Lyrurus tetrix) have been reported from both Central Europe and the continuous boreal forests of Fennoscandia. While intensified land-use is assumed to be the underlying cause of these declines, the mechanisms are not yet understood. Predation is the proximate cause of mortality of eggs, chicks and adults throughout capercaillie and black grouse ranges, but the link between predation and habitat and/or climate change remains unclear. To investigate temporal trends in reproductive output of woodland grouse, we collated previously published and unpublished data of reproduction in capercaillie and black grouse throughout their ranges from 1930 to 2012. We show that, overall, reproductive success has decreased and stabilized at low levels in most regions whilst capercaillie reproductive output in Scotland is still declining. With today’s net reproduction, capercaillie and black grouse adult survival is too low to compensate for reproduction declines. Consequently, populations are expected to further decline unless reproductive performances improve. We put our findings in the context of changes in land use, climate and generalist predator numbers. By critically reviewing how these factors limit reproductive success in capercaillie and black grouse, we hope to shed light on the underlying mechanisms causing the decline. Our results imply that measures should be undertaken to reduce mortality of capercaillie and black grouse chicks and eggs. We suggest that future studies should aim to better understand which predators limit capercaillie and black grouse populations and how predation rates are mediated by continuously changing habitat and climate.

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Natal Dispersal and Lek Fidelity of Sage Grouse

The Auk ◽

10.1093/auk/102.3.621 ◽

1985 ◽

Vol 102 (3) ◽

pp. 621-627 ◽

Cited By ~ 54

Author(s):

Peter O. Dunn ◽

Clait E. Braun

Keyword(s):

Reproductive Success ◽

Centrocercus Urophasianus ◽

Natal Dispersal ◽

Attendance Rates ◽

Sage Grouse ◽

Male And Female ◽

Cold Spring

Abstract Natal dispersal and lek fidelity (attendance within and between years) of Sage Grouse (Centrocercus urophasianus) were studied on Cold Spring Mountain, northwestern Colorado, from July 1981 through May 1984. Female Sage Grouse followed the typical avian pattern of dispersing farther than males. However, there was no difference between proportions of male and female yearling grouse attending the lek closest to their juvenile banding location. Fifteen percent of all individually marked juveniles (24/157 birds) were known to have attended leks as yearlings. There was no difference between yearling and adult lek attendance rates for either sex; however, females attended leks less often than males. Yearling females, but not yearling males, visited 2 or more leks more often than adults. These differences may be related to yearlings' inexperience with breeding or to a strategy to enhance reproductive success.

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Archaeological Bird Bones from Chapin Mesa, Mesa Verde National Park

Memoirs of the Society for American Archaeology ◽

10.1017/s0081130000004494 ◽

1965 ◽

Vol 19 ◽

pp. 156-160

Author(s):

Lyndon L. Hargrave

Keyword(s):

National Park ◽

Bird Species ◽

Sage Grouse ◽

Sandhill Crane ◽

Mesa Verde ◽

Common Raven ◽

Temporal And Spatial

AbstractBird bones from sites on Chapin Mesa, in the collection of the Mesa Verde Museum, were examined. From such a study, it is possible to learn something about the distribution (temporal and spatial) of certain bird species, the use made of them by prehistoric peoples, and certain aspects of the ecology. Birds identified included Whistling Swan, Mallard or Mexican Duck, Hawk, Sage Grouse, Turkey, Sandhill Crane, Great Horned Owl, Black-billed Magpie, Common Raven, and Common Crow.

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