Reproductive Success of Wood Thrushes in Forest Fragments in Northern Indiana

AbstractI monitored 278 Wood Thrush (Hylocichla mustelina) nests in 14 forest fragments (range 7 to 500 ha) in northern Indiana to explore patterns of brood parasitism by Brown-headed Cowbirds (Molothrus ater), nest predation, and reproductive success. Density of thrushes was negatively related to area of forest fragments. Cowbirds were common throughout the landscape, but I found no relationship between their abundance and forest area. Overall, 90% of the thrush nests were parasitized by cowbirds (x̄ = 2.4 cowbird eggs per nest). The number of cowbird eggs per thrush nest was not related to forest area, abundance of host species, or distance to a forest edge but was positively related to thrush abundance. Nest predation rates averaged 58% and were lower than those reported in much of neighboring Illinois but also were unrelated to forest area and distance to a forest edge. The combination of cowbird parasitism and nest predation resulted in relatively low reproductive success (x̄ = 0.6 thrush fledglings per nesting attempt). I estimated that Wood Thrushes in northern Indiana made an average of three nesting attempts per breeding season (based on 17 color-marked females) and had relatively low seasonal fecundity (x̄ = 0.9 female fledglings per adult female per season). Nonetheless, considerable annual variation in seasonal fecundity suggested that some sites exceeded the source-sink threshold in some years. Regardless, the overall landscape appeared to be part of a regional sink for Wood Thrushes, although its negative influence on regional demography was not as severe as elsewhere in the midwestern United States. The poor demographic balance in much of the agriculturally dominated Midwest suggests that conservation efforts for Wood Thrushes and other Nearctic-Neotropical migrants should be directed at preserving and enhancing possible source habitats in regions where parasitism by cowbirds and nest predation are reduced.

Download Full-text

Impacts of Housing Developments on Wood Thrush Nesting Success in Hardwood Forest Fragments

The Condor ◽

10.1093/condor/107.1.97 ◽

2005 ◽

Vol 107 (1) ◽

pp. 97-106 ◽

Cited By ~ 2

Author(s):

Judith Phillips ◽

Erica Nol ◽

Dawn Burke ◽

Wendy Dunford

Keyword(s):

Nest Predation ◽

Molothrus Ater ◽

Forest Edge ◽

Forest Fragments ◽

Hylocichla Mustelina ◽

Wood Thrush ◽

Housing Developments ◽

Las Casas ◽

Wood Thrushes ◽

Small Forest

Abstract We studied the impacts of low density, exurban housing developments on Wood Thrushes (Hylocichla mustelina) breeding in small forest fragments in two regions of rural southern Ontario. In both regions, Wood Thrushes breeding in woodlots with embedded houses (housing penetrating the forest border) experienced significantly higher rates of parasitism by Brown-headed Cowbirds (Molothrus ater) than Wood Thrushes breeding in woodlots with adjacent houses (houses within 100 m of the forest edge), or undeveloped woodlots (no houses within 100 m of the forest edge). Wood Thrushes breeding in Peterborough area woodlots with embedded or adjacent houses experienced significantly increased rates of nest predation compared to Wood Thrushes breeding in undeveloped woodlots. This increased nest predation resulted in significant reductions in seasonal productivity in developed woodlots. No increase in nest predation was experienced by Wood Thrushes nesting in developed woodlots in the Ottawa region. The effects of housing developments appear to be region-specific and may depend on other factors influencing the overall abundance of cowbirds. Impactos de la Construcción de Viviendas en el Éxito de Nidificación de Hylocichla mustelina en Fragmentos de Bosque Resumen. Estudiamos los impactos de la construcción en baja densidad de viviendas peri-urbanas sobre individuos de Hylocichla mustelina que se encontraron criando en fragmentos pequeños de bosque en dos regiones rurales del sur de Ontario. En ambas regiones, los individuos de H. mustelina que se reprodujeron en bosques donde había casas inmersas (que penetraban el borde del bosque) experimentaron tasas de parasitismo por Molothrus ater significativamente mayores que los individuos criando en bosques con casas adyacentes (dispuestas a menos de 100 m del borde del bosque), o en bosques no alterados por la presencia de casas (a más de 100 m del borde del bosque). Los individuos de H. mustelina que se encontraron criando en áreas boscosas de Peterborough, donde las casas estaban adentro o adyacentes al bosque, experimentaron incrementos significativos en las tasas de depredación de nidos comparados con individuos que criaron en bosques no alterados. Este incremento en la depredación de nidos llevó a reducciones significativas en la productividad estacional en los bosques con viviendas. No registramos un incremento en la depredación de nidos de H. mustelina en bosques con viviendas en la región de Ottawa. Los efectos de la construcción de viviendas parecen estar relacionados de modo específico con la región y podrían depender de otros factores que influencian la abundancia de M. ater.

Download Full-text

Avian Reporting Rates in Chugcheongnam Province, South Korea Depend on Distance from Forest Edge, Size of Trees, and Size of Forest Fragments

Forests ◽

10.3390/f10050364 ◽

2019 ◽

Vol 10 (5) ◽

pp. 364

Author(s):

Jang ◽

Seol ◽

Chung ◽

Sagong ◽

Lee

Keyword(s):

South Korea ◽

Size Structure ◽

Species Abundance ◽

Bird Species ◽

Forest Edge ◽

Forest Area ◽

Forest Fragments ◽

Bird Abundance ◽

Forest Condition ◽

Abundance And Diversity

Forests provide bird communities with various resources, including food and habitats. Thus, forest attributes, such as size, structure, and species composition, influence the distribution and dynamics of bird species. This study was conducted to examine the association between forest condition, bird species abundance, and diversity within Chungcheongnam Province, South Korea. Zero-inflated binomial regression models were used to analyze a total of 1646 sampling points of abundance and diversity. Forest area, distance to forest edge, and tree size class were selected as covariates. Negative associations between forest area and overall bird abundance and species richness were indicated, whereas distance to forest edge was not a significant factor. This insignificance may be attributed to the relatively small, fragmented, and homogenous forest areas across the studied region. Results for individual bird species indicated that six out of the 35 major bird species had significant associations to the forest edge and three species showed a preference for the interior of the forest. The results of this study imply that other factors, such as food availability and biotic interaction, are more important when determining habitat preference in a relatively homogenous area with a long history of human disturbance.

Download Full-text

The influence of subcolony-scale nesting habitat on the reproductive success of Adélie penguins

Scientific Reports ◽

10.1038/s41598-021-94861-7 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Annie E. Schmidt ◽

Grant Ballard ◽

Amélie Lescroël ◽

Katie M. Dugger ◽

Dennis Jongsomjit ◽

...

Keyword(s):

Reproductive Success ◽

Colony Size ◽

Nest Predation ◽

Size Variation ◽

Area Ratio ◽

Slope Aspect ◽

Nesting Habitat ◽

Terrain Attributes ◽

Small Colony ◽

Adélie Penguins

AbstractGroup-size variation is common in colonially breeding species, including seabirds, whose breeding colonies can vary in size by several orders of magnitude. Seabirds are some of the most threatened marine taxa and understanding the drivers of colony size variation is more important than ever. Reproductive success is an important demographic parameter that can impact colony size, and it varies in association with a number of factors, including nesting habitat quality. Within colonies, seabirds often aggregate into distinct groups or subcolonies that may vary in quality. We used data from two colonies of Adélie penguins 73 km apart on Ross Island, Antarctica, one large and one small to investigate (1) How subcolony habitat characteristics influence reproductive success and (2) How these relationships differ at a small (Cape Royds) and large (Cape Crozier) colony with different terrain characteristics. Subcolonies were characterized using terrain attributes (elevation, slope aspect, slope steepness, wind shelter, flow accumulation), as well group characteristics (area/size, perimeter-to-area ratio, and proximity to nest predators). Reproductive success was higher and less variable at the larger colony while subcolony characteristics explained more of the variance in reproductive success at the small colony. The most important variable influencing subcolony quality at both colonies was perimeter-to-area ratio, likely reflecting the importance of nest predation by south polar skuas along subcolony edges. The small colony contained a higher proportion of edge nests thus higher potential impact from skua nest predation. Stochastic environmental events may facilitate smaller colonies becoming “trapped” by nest predation: a rapid decline in the number of breeding individuals may increase the proportion of edge nests, leading to higher relative nest predation and hindering population recovery. Several terrain covariates were retained in the final models but which variables, the shapes of the relationships, and importance varied between colonies.

Download Full-text

Edge Effects on the Epiphytic Lichen Flora of Picea Abies in Middle Boreal Finland

The Lichenologist ◽

10.1006/lich.2000.0282 ◽

2000 ◽

Vol 32 (4) ◽

pp. 387-398 ◽

Cited By ~ 48

Author(s):

Laura Kivistö ◽

Mikko Kuusinen

Keyword(s):

Species Diversity ◽

Picea Abies ◽

Forest Edge ◽

Lichen Species ◽

Forest Fragments ◽

Epiphytic Lichen ◽

Clear Cut ◽

Old Growth Forest ◽

Forest Margin ◽

Lichen Flora

AbstractThe edge effect of large clear-cuts on the epiphytic lichen flora of Picea abies in old-growth forest fragments was studied at three south-exposed and four north-exposed forest clear-cut edges in middle boreal Finland. The sampling of the species cover on trunk bases was carried out along four transects parallel to the forest margin: (1) at the forest margin, (2) 10 m from the margin, (3) 20 m from the margin and (4) 50 m from the margin. In addition, control trees were sampled > 100 m from nearest edge. Our results showed that the epiphytic lichen species diversity was lower at the forest margin than in the forest interior for sunny south-facing edges, while the species diversity in north-exposed edges was independent of the distance from the forest margin. The cover of a common and abundant lichen species, Parmeliopsis ambigua, was slightly higher at the forest edge and decreased inside the forest for both south-exposed and north-exposed edges.

Download Full-text

Influence of weather on two insectivorous bats in a temperate Pacific Northwest rainforest

Canadian Journal of Zoology ◽

10.1139/z08-146 ◽

2009 ◽

Vol 87 (2) ◽

pp. 132-138 ◽

Cited By ~ 36

Author(s):

D. W. Burles ◽

R. M. Brigham ◽

R. A. Ring ◽

T. E. Reimchen

Keyword(s):

Reproductive Success ◽

Pacific Northwest ◽

Weather Conditions ◽

Negative Influence ◽

Myotis Lucifugus ◽

Insectivorous Bats ◽

Ambient Temperatures ◽

The Pacific ◽

Adverse Weather ◽

Insect Activity

Adverse weather conditions frequently have a significant negative influence on survival and reproductive success of insectivorous bats. Low ambient temperatures increase the energetic costs of maintaining euthermia and reduces insect activity, while precipitation likely adds “clutter” making prey more difficult to detect using echolocation. We studied two species of insectivorous bats, Myotis lucifugus (LeConte, 1831) and Myotis keenii (Merriam, 1895), in the Pacific Northwest of Canada, a region that experiences frequent cool, wet weather during spring and summer. Our study took place during the El Niño – La Niña cycle of 1998–1999, which resulted in contrasting years. The summer of 1998 was unusually warm and dry, while the summer of 1999 was unusually cool and wet. We predicted that both species would be adversely affected by the cool, wet conditions of 1999, resulting in prolonged gestation, late fledging of young, and lower reproductive success. However, this was not the case. Myotis lucifugus did experience delays in reproductive timing and lower reproductive success in 1999, as predicted, whereas M. keenii experienced much shorter gestations, earlier fledgings, and no difference in reproductive success between years. We hypothesize that the ability of M. keenii to glean prey enables it to better cope with cool, wet conditions.

Download Full-text

Demography of Bell's Vireos in Missouri Grassland-Shrub Habitats

The Auk ◽

10.1093/auk/117.4.925 ◽

2000 ◽

Vol 117 (4) ◽

pp. 925-935 ◽

Cited By ~ 10

Author(s):

Joel M. Budnik ◽

Mark R. Ryan ◽

Frank R. Thompson III

Keyword(s):

Nest Predation ◽

Molothrus Ater ◽

Nesting Success ◽

Growth Potential ◽

Population Declines ◽

Annual Survival ◽

Rate Of Increase ◽

Study Population ◽

Breeding Seasons ◽

Seasonal Fecundity

Abstract Numbers of Bell's Vireos (Vireo bellii) have declined throughout much of the breeding range in recent years, yet little information exists to determine factors that are causing these declines. We studied Bell's Vireos nesting in grassland-shrub habitats at two study areas in central Missouri to determine reproductive performance, survival, and population growth potential. Birds were color banded and observed during the breeding seasons of 1996, 1997, and 1998 to determine seasonal fecundity. We monitored 124 breeding pairs (127 pair years) and 213 nests. Density declined from 1.00 to 0.80 territories per 10 ha at the first site and increased from 1.11 to 1.33 at the second site during the study. Mean nesting success was 31 ± SE of 0.03% overall and ranged from 13 to 42% among years and study areas; 57% of the pairs fledged at least one young. Low annual production was a function of high rates of nest predation (41% of all nests observed, accounting for 44 to 78% of daily nest mortality annually) and nest parasitism by Brown-headed Cowbirds (Molothrus ater; 29% of nests observed, 17 to 37% of daily nest mortality annually). Mean seasonal fecundity was 1.60 young fledged per pair per year (range 1.00 to 1.79). Annual survival of adults was 61 ± 0.04% and was higher than previously reported. We used our estimates of seasonal fecundity and annual survival of adults to determine the finite rate of increase (λ) for our study population. Our study areas seemingly comprised sink habitats (λ = 0.85). Thus, the vireos on our study areas likely were limited by low reproductive success. Population declines also may be caused by habitat loss, which highlights the need for investigation of historical and current rates of loss of grassland-shrub habitat.

Download Full-text

Reproduction and Offspring Sex Ratios Differ Markedly among Closely Related Hyperparasitoids Living in the Same Microhabitats

Journal of Insect Behavior ◽

10.1007/s10905-019-09730-z ◽

2019 ◽

Vol 32 (3) ◽

pp. 243-251 ◽

Cited By ~ 1

Author(s):

Jeffrey A. Harvey ◽

Lucas de Haan ◽

Oriol Verdeny-Vilalta ◽

Bertanne Visser ◽

Rieta Gols

Keyword(s):

Reproductive Success ◽

Sex Ratios ◽

Reproductive Traits ◽

Female Offspring ◽

Forest Edge ◽

Cotesia Glomerata ◽

Small Scale ◽

Lifetime Reproductive Success ◽

Closely Related Species ◽

Offspring Sex

Abstract Closely related species in nature usually exhibit very similar phylogenetically conserved traits, such as reproduction, behavior and development. Here, we compared fecundity schedules, lifetime reproductive success and offspring sex ratios in three congeneric facultative hyperparasitoid wasps that exhibit several overlapping traits and which co-occur in the same small-scale habitats. Gelis agilis, G. proximus and G. hortensis are abundant in meadows and forest edge habitats in the Netherlands. Gelis agilis is asexual (all female), whereas the other two species reproduce sexually. Here they developed on cocoons of the primary parasitoid Cotesia glomerata. When provided with unlimited hosts, lifetime reproductive success was three times higher in G. proximus than in G. agilis with G. hortensis producing intermediate numbers of offspring. All three species depleted their teneral reserves during their lives. Females of G. proximus and G. hortensis lived significantly longer than females of G. agilis. Offspring sex ratios in young G. proximus mothers were female-biased and marginally male-biased in G. hortensis. As mothers aged, however, the ratio of male:female progeny produced rapidly increased until no daughters emerged later in life. Our results reveal significant differences in reproductive traits among the three species despite them co-occurring in the same microhabitats, being very closely related and morphologically similar. The increase in the production of male progeny by Gelis mothers over time suggests a depletion in sperm number or viability with age. This is especially interesting, given that Gelis species are among the least fecund parasitoids thus far studied. It is likely that in the field most Gelis mothers are probably only able to parasitize a few hosts and to maintain the production of female offspring.

Download Full-text

Nesting With The Wasp Ropalidia Cincta Increases Nest Success of Red-Cheeked Cordonbleu (Uraeginthus Bengalus) in Ghana

The Auk ◽

10.1093/auk/123.4.1022 ◽

2006 ◽

Vol 123 (4) ◽

pp. 1022-1037 ◽

Cited By ~ 4

Author(s):

Paul Beier ◽

Agba Issahaku Tungbani

Keyword(s):

Reproductive Success ◽

Nest Predation ◽

Northern Ghana ◽

Social Hymenoptera ◽

Tropical Regions ◽

Nest Sites ◽

Wasp Nests ◽

Habitat Feature ◽

Working Hypotheses ◽

Rule Out

AbstractAssociations between birds and social Hymenoptera (ants, wasps, bees) are common in tropical regions and are usually assumed to be commensal relationships that benefit birds but neither help nor harm the arthropods. However, benefits to birds have been documented in only four such associations, and no previous research has rigorously investigated costs or benefits to associated hymenopterans. We followed the nesting cycles of an estrildid finch, the Red-cheeked Cordonbleu (Uraeginthus bengalus), and a common nesting associate, the wasp Ropalidia cincta, during 2002 and 2003 in northern Ghana to compare reproductive success of birds and wasps nesting in association with that of birds and wasps nesting separately. Red-cheeked Cordonbleus and wasps nested together in the same tree 3.7 × as often as expected if nesting decisions were made independently, with 74% of bird nests and 74% of wasp colonies occurring in associations. Bird nesting was initiated ≈33 days after founding of an associated wasp colony; bird nests and wasp colonies were, on average, 42 cm apart. In both years, Red-cheeked Cordonbleus in nesting associations with wasps were twice as likely to fledge young as birds nesting in trees without wasps. Reduced predation was apparently a major reason for increased fledging success: we documented four cases of nest predation on 122 Red-cheeked Cordonbleu nests associated with wasps, and 11 cases on 90 nests not associated with wasps. Association with birds did not affect the success of wasp colonies. Although our observational study cannot rule out the possibility that both species coincidentally shared a preference for a habitat feature in limited supply, suitable nest sites did not appear to be limiting (74% of potential nest trees had neither bird nor wasp nests). Reproductive success of Red-cheeked Cordonbleu populations in this region may be limited by the number of available wasp colonies. By designing our study to address four working hypotheses (commensalism, mutualism, parasitism, coincidence of habitat preference), we have provided strong evidence that this relationship is commensal.Augmentation du Succès de Nidification de Uraeginthus bengalus Nichant avec des Guêpes Ropalidia cincta au Ghana

Download Full-text