scholarly journals Brown-headed Cowbird, Molothrus ater, Parasitism and Abundance in the Northern Great Plains

2007 ◽  
Vol 121 (3) ◽  
pp. 239 ◽  
Author(s):  
Lawrence D. Igl ◽  
Douglas H. Johnson
Keyword(s):  
Great Plains ◽  
Molothrus Ater ◽  
Bird Community ◽  
Northern Great Plains ◽  
Breeding Bird ◽  
Host Parasite Interactions ◽  
Parasitism Rates ◽  
Cowbird Parasitism ◽  
The Mean ◽  
Host Parasite

The Brown-headed Cowbird (Molothrus ater) reaches its highest abundance in the northern Great Plains, but much of our understanding of cowbird ecology and host-parasite interactions comes from areas outside of this region. We examine cowbird brood parasitism and densities during two studies of breeding birds in the northern Great Plains during 1990–2006. We found 2649 active nests of 75 species, including 746 nonpasserine nests and 1902 passerine nests. Overall, <1% of nonpasserine nests and 25% of passerine nests were parasitized by Brown-headed Cowbirds. Although the overall frequency of cowbird parasitism in passerine nests in these two studies is considered moderate, the frequency of multiple parasitism among parasitized nests was heavy (nearly 50%). The mean number of cowbird eggs per parasitized passerine nest was 1.9 ± 1.2 (SD; range = 1–8 cowbird eggs). The parasitism rates were 9.5% for passerines that typically nest in habitats characterized by woody vegetation, 16.4% for grassland-nesting passerines, 4.7% for passerines known to consistently eject cowbird eggs, and 28.2% for passerines that usually accept cowbird eggs. The Red-winged Blackbird (Agelaius phoeniceus) was the most commonly parasitized species (43.1% parasitism, 49.6% multiple parasitism, 71.2% of all cases of parasitism). Passerine nests found within areas of higher female cowbird abundance experienced higher frequencies of cowbird parasitism than those found in areas of lower female cowbird abundance. Densities of female cowbirds were positively related to densities and richness of other birds in the breeding bird community.

scholarly journals Conventional oil and natural gas infrastructure increases brown-headed cowbird ( Molothrus ater ) relative abundance and parasitism in mixed-grass prairie

2017 ◽  
Vol 4 (7) ◽  
pp. 170036 ◽  
Author(s):  
Jacy Bernath-Plaisted ◽  
Heather Nenninger ◽  
Nicola Koper
Keyword(s):  
Natural Gas ◽  
Great Plains ◽  
Relative Abundance ◽  
Brood Parasitism ◽  
Molothrus Ater ◽  
Rapid Expansion ◽  
Northern Great Plains ◽  
Brood Parasite ◽  
Parasitism Rates ◽  
Oil And Natural Gas

The rapid expansion of oil and natural gas development across the Northern Great Plains has contributed to habitat fragmentation, which may facilitate brood parasitism of ground-nesting grassland songbird nests by brown-headed cowbirds ( Molothrus ater ), an obligate brood parasite, through the introduction of perches and anthropogenic edges. We tested this hypothesis by measuring brown-headed cowbird relative abundance and brood parasitism rates of Savannah sparrow ( Passerculus sandwichensis ) nests in relation to the presence of infrastructure features and proximity to potential perches and edge habitat. The presence of oil and natural gas infrastructure increased brown-headed cowbird relative abundance by a magnitude of four times, which resulted in four times greater brood parasitism rates at infrastructure sites. While the presence of infrastructure and the proximity to roads were influential in predicting brood parasitism rates, the proximity of perch sites was not. This suggests that brood parasitism associated with oil and natural gas infrastructure may result in additional pressures that reduce productivity of this declining grassland songbird.

Comparing Brassica oilseed crop productivity under contrasting N fertility regimes in the semiarid northern Great Plains

2003 ◽  
Vol 83 (3) ◽  
pp. 489-497 ◽  
Author(s):  
P. R. Miller ◽  
S. V. Angadi ◽  
G. L. Androsoff ◽  
B. G. McConkey ◽  
C. L. McDonald ◽  
...  
Keyword(s):  
Great Plains ◽  
Seed Yield ◽  
Shoot Biomass ◽  
Northern Great Plains ◽  
Oilseed Crop ◽  
Available N ◽  
Brassica Spp ◽  
Primary Yield ◽  
The Mean ◽  
N Fertility

We compared the growth and yield of five Brassica spp. genotypes [two B.juncea (L.) Coss., two B. napus L. and one B. rapa L.] in 11 environments spanning two degrees of latitude and longitude in southern Saskatchewan in 1996–1998. All entries were managed with three levels of N fertility at each site. Plant height for the canola-quality B. juncea breeding line J904316 was 21% greater than the mean of the other genotypes, but shoot biomass did not differ for the same comparison. Cutlass Oriental mustard consistently yielded greatest across all environments while the yield of J904316 was highly variable among environments. The mean seed yield of Cutlass was 12% greater than the highest-yielding B. napus cultivar and 32% greater than the B. rapa cultivar, and had a greater harvest index. Earlier genotypes yielded greater than late-flowering and maturing genotypes within B. juncea and B. napus, but the earliest genotype, Maverick (B. rapa), yielded lower than all other genotypes. All Brassica spp. genotypes were responsive to N fertilization, and high total available N (average = 109, range = 91 to 131 kg N ha-1) was generally required to maximize seed yield, but not shoot biomass, under the conditions of this study. Pod density was the primary yield component influenced by N level. This study illustrates the potential adaptive advantage of B. juncea on the semiarid northern Great Plains. Key words: Brassica, canola, genotype, mustard, N fertility, semiarid, northern Great Plains

Parasitism by Brown-headed Cowbirds and productivity of House Finch hosts

1998 ◽  
Vol 76 (9) ◽  
pp. 1714-1721 ◽  
Author(s):  
Daniel R Kozlovic
Keyword(s):  
Clutch Size ◽  
Reproductive Output ◽  
Molothrus Ater ◽  
Carpodacus Mexicanus ◽  
House Finch ◽  
House Finches ◽  
Cowbird Parasitism ◽  
The Mean ◽  
Egg Removal ◽  
Established Population

The effect of parasitism by Brown-headed Cowbirds (Molothrus ater) on the reproductive success of a recently established population of House Finches (Carpodacus mexicanus) was studied at St. Catharines, Ontario, during 1983-1985. House Finches began to colonize Ontario in 1972 and breeding was first observed there in 1978. Cowbirds laid in 40.2% of House Finch nests and parasitism was most prevalent during the peak of House Finch nesting. Clutches initiated early in the season were free of cowbird eggs. Most (76%) House Finch nests were parasitized within 2 days after the first House Finch egg was laid. Parasitized House Finch nests contained 1-3 cowbird eggs and the mean number of cowbird eggs per parasitized nest was 1.30. Frequency of multiple parasitism was 24.2% and the number of cowbird eggs per nest was not significantly different from a truncated Poisson distribution. Cowbird parasitism depressed House Finch clutch size and number of hatchlings and fledglings, but the proportion of surviving eggs in parasitized nests that yielded hatchlings and fledglings was not influenced by parasitism. Overall growth of House Finch nestlings did not differ significantly between parasitized and unparasitized nests. Thus, House Finches were able to successfully rear most of their young irrespective of parasitism. The decrease in reproductive output of House Finches was mainly due to egg removal by cowbirds, which effectively reduced the clutch size of parasitized nests by about 1 House Finch egg.

scholarly journals Geographic Variation in Brown-Headed Cowbird (Molothrus Ater) Parasitism on Dickcissels (Spiza Americana) in Great Plains Tallgrass Prairie

The Auk ◽  
2005 ◽  
Vol 122 (2) ◽  
pp. 648-660 ◽  
Author(s):  
William E. Jensen ◽  
Jack F. Cully
Keyword(s):  
Geographic Variation ◽  
Great Plains ◽  
Tallgrass Prairie ◽  
Brood Parasitism ◽  
Molothrus Ater ◽  
Grassland Birds ◽  
Spiza Americana ◽  
Flint Hills ◽  
Cowbird Parasitism ◽  
Study Sites

Abstract The incidence of brood parasitism by Brown-headed Cowbirds (Molothrus ater; hereafter “cowbirds“) within host species typically reflects the continental pattern in cowbird abundance across North America, where parasitism is heaviest in the Great Plains. However, we found considerable variation in cowbird parasitism on Dickcissel (Spiza americana) nests within a subregion of the Great Plains (the Flint Hills), where the highest levels of cowbird parasitism on grassland bird nests had been previously reported. Local parasitism frequencies on Dickcissel nests varied latitudinally across the Flint Hills, ranging from 0% to 92% of nests parasitized. Interestingly, we found no obvious patterns in habitat or host attributes that were associated with this steep geographic gradient in brood parasitism. Cowbird parasitism on Dickcissel nests was not correlated with the vertical density of local prairie vegetation, mean nest distance to edge, proportion of forest to grassland habitat surrounding study sites (≤5 to 10 km), geographic variation in host abundance, or Dickcissel density or nest initiation dates. Parasitism frequencies and intensities (number of cowbird eggs per parasitized nest) on Dickissel nests were only significantly related to variation in local female cowbird density. Dickcissel clutch size and apparent fledging success were negatively correlated with local cowbird parasitism levels. Geographic patterns in cowbird abundance within and among regions should be considered when establishing conservation areas for grassland birds or other cowbird hosts of concern.

scholarly journals Aggressiveness of Stagonospora nodorum Isolates Obtained from Wheat in the Northern Great Plains

Plant Disease ◽  
1997 ◽  
Vol 81 (9) ◽  
pp. 1027-1031 ◽  
Author(s):  
J. M. Krupinsky
Keyword(s):  
Great Plains ◽  
Symptom Severity ◽  
Lesion Size ◽  
Stagonospora Nodorum ◽  
Northern Great Plains ◽  
Mild Symptom ◽  
Wheat Seedlings ◽  
The Mean ◽  
Wheat Leaves ◽  
Main Effects

Isolates of Stagonospora nodorum, obtained from diseased wheat leaves collected in fields in Montana, North Dakota, and South Dakota, were tested on detached seedling leaves of wheat and found to be pathogenic. Differences among isolates chosen at random were detected in the first phase of the inoculations. Isolates associated with severe and mild symptom severity, as measured by lesion size, were selected in phase two. Isolates associated with severe and mild symptom severity were statistically differentiated in phase three. The ability of isolates to cause significant differences in symptom severity was interpreted as differences in aggressiveness. The differences among isolates detected with detached leaf experiments was confirmed with glasshouse inoculations of seedling wheat plants. The high aggressive isolates consistently produced higher symptom severity on wheat seedlings, as measured by percentage necrosis, than low aggressive isolates. Cultivars were consistently differentiated with isolates associated with different levels of aggressiveness. With unselected isolates, the cultivar × isolate interaction was nonsignificant, indicating a lack of specificity. With high and low aggressive isolates, the cultivar × isolate interaction was significant. Considering that the magnitude of the mean squares for interactions were rather low compared to the main effects, it is speculated either that specificity is detected with the present isolates but only at a low level, or that specificity is apparent only when isolate extremes are tested. With studying isolates in phases rather than random comparisons, fungal isolates associated the high and low aggressiveness can be identified and, once identified, isolates from different hosts or geographical areas can be compared in an efficient and meaningful manner.

scholarly journals Host-parasite interaction explains variation in prevalence of avian haemosporidians at the community level

2018 ◽  
Author(s):  
L. Garcia-Longoria ◽  
A. Marzal ◽  
F. de Lope ◽  
L. Z. Garamszegi
Keyword(s):  
Host Species ◽  
Bird Species ◽  
Ecological Factors ◽  
Bird Community ◽  
Parasite Prevalence ◽  
Host Community ◽  
Dual Nature ◽  
Host Parasite Interactions ◽  
Avian Haemosporidians ◽  
Host Parasite

ABSTRACTParasites are a selective force that shape host community structure and dynamics, but host communities can also influence parasitism. Understanding the dual nature from host-parasite interactions can be facilitated by quantifying the variation in parasite prevalence (i.e. the proportion of infected host individuals in a population) among host species and then comparing that variation to other ecological factors that are known to also shape host communities. Avian haemosporidian parasites (e.g. Plasmodium and Haemoproteus) are abundant and widespread representing an excellent model for the study of host-parasite interactions. Several geographic and environmental factors have been suggested to determine prevalence of avian haemosporidians in bird communities. However, much remains to be known regarding whether host and parasite traits, represented by phylogenetic distances among species and degree of specialization in host-parasite relationships, can influence parasite prevalence. The aims of this study were to analyze factors affecting prevalence in a bird community and to test whether the degree of parasite specialization on their hosts is determined by host traits. Our statistical analyses suggest that prevalence is mainly determined by the interaction between host species and parasite lineages where tolerance and/or susceptibility to parasites plays an essential role. Additionally, we found that although some of the parasite lineages infected a low number of bird species, the species they infected were distantly related and therefore the parasites themselves should not be considered typical host specialists. Prevalence was higher for generalist than for specialist parasites in some, but not all, host species. These results suggest that prevalence mainly results from the interaction between host immune defences and parasite exploitation strategies wherein the result of an association between particular parasite lineages and particular host species is idiosyncratic.

scholarly journals Metrics for conservation success: using the ‘Bird-Friendliness Index’ to evaluate grassland and aridland bird community resilience across the Northern Great Plains ecosystem

2019 ◽  
Author(s):  
Nicole L. Michel ◽  
Curtis Burkhalter ◽  
Chad B. Wilsey ◽  
Matt Holloran ◽  
Alison Holloran ◽  
...  
Keyword(s):  
Great Plains ◽  
Habitat Management ◽  
Management Practices ◽  
Temporal Trends ◽  
Bird Community ◽  
Community Resilience ◽  
Community Response ◽  
Bird Communities ◽  
Northern Great Plains ◽  
Management Plans

AbstractAimEvaluating conservation effectiveness is essential to protect at-risk species and to maximize the limited resources available to land managers. Over 60% of North American grassland and aridlands have been lost since the 1800s. Birds in these habitats are among the most imperiled in North America, yet most remaining habitats are unprotected. Despite the need to measure impact, conservation efforts on private and working lands are rarely evaluated, due in part to limited availability of suitable methods.LocationNorthern Great PlainsMethodsWe developed a novel metric to evaluate grassland and aridland bird community response to habitat management practices, the Bird-Friendliness Index (BFI), consisting of density estimates of grassland and aridland birds weighted by conservation need and a functional diversity metric to incorporate resiliency. We used the BFI to inform three assessments: 1) a spatial prioritization to identify ecologically significant areas for grassland and aridland birds, 2) estimation of temporal trends in grassland and aridland bird community resilience, and 3) evaluation of the effects of land management practices on grassland and aridland bird communities.ResultsThe most resilient bird communities were found in the Prairie Potholes region of Alberta, Saskatchewan, northern Montana, and North Dakota, and the lowest BFI values in the southern and western regions of the Northern Great Plains. BFI values varied little over time on average, but trends varied regionally, largely in response to interannual relative variability in grassland and aridland bird densities.Main conclusionsBFI values increased in response to simulated habitat management, suggesting that practices recommended for use in bird-friendly grassland habitat management plans will increase the abundance and resilience of the grassland and aridland bird community, and will be detected using the BFI. The BFI is a tool by which conservationists and managers can carry out accountable conservation now and into the future.

scholarly journals Metrics for conservation success: Using the “Bird‐Friendliness Index” to evaluate grassland and aridland bird community resilience across the Northern Great Plains ecosystem

2020 ◽  
Vol 26 (12) ◽  
pp. 1687-1702
Author(s):  
Nicole L. Michel ◽  
Curtis Burkhalter ◽  
Chad B. Wilsey ◽  
Matt Holloran ◽  
Alison Holloran ◽  
...  
Keyword(s):  
Great Plains ◽  
Bird Community ◽  
Community Resilience ◽  
Northern Great Plains

scholarly journals Breeding avifauna of mature forest stands in the Borki Forest and its dynamics at the turn of the 21st century

2016 ◽  
Vol 77 (3) ◽  
pp. 239-255
Author(s):  
Grzegorz Rąkowski ◽  
Krzysztof Czarnocki ◽  
Joanna Ukalska
Keyword(s):  
Coniferous Forest ◽  
Bird Species ◽  
Bird Community ◽  
Species Group ◽  
Mapping Technique ◽  
Total Density ◽  
Forest Stands ◽  
Population Densities ◽  
Breeding Bird ◽  
The Mean

Abstract The composition and structure of the breeding bird community in the Borki Forest in north-eastern Poland were investigated during two separate periods: 1994–1996 and 2012–2014. Bird censuses were carried out in three plots located in mature oak-hornbeam, ash-alder and mixed coniferous forest stands. A standard combined mapping technique for estimating the number of breeding birds was applied. A total of 74 bird species bred at least once within any plot during 1994–1996 or 2012–2014. The structure of the bird assemblages on particular plots displayed a high degree of similarity, exceeding 75%, which means that they represent essentially the same bird community. However, the investigated assemblages have changed substantially over the 20 years. Both, the number of breeding bird species and the population densities on all plots, were much higher in 2012–2014 than in 1994–1996. The mean number of breeding species on all plots was over 50% higher in 2012–2014 than in 1994–1996, whereas the mean total density of breeding pairs increased by more than 60%. Total population densities on the plots increased as a result of an increase in population densities of individual bird species combined with an increase in the number of breeding species. Due to different rates of population growth for certain species, also the composition of dominating species group have changed. The observed changes in the avifauna of the Borki Forest were most probably due to an enrichment of the forest habitats structure, which was caused by natural factors, such as ageing of forest stands, forest succession and a change in water regime by beaver dams, as well as by forest management, including group felling within or in the vicinity of plots and uncovering of the forest edge.

Sign in / Sign up

Export Citation Format

Share Document