Nesting Success of Scissor-Tailed Flycatchers (Tyrannus forficatus) at a Wind Farm in Northern Texas (original) (raw)
Related papers
2011
Ornithologists have extensively studied nest predation because predators are responsible for most nest failures (Ricklefs 1969, Martin 1995, Newton 1998). Factors correlated with variation in the occurrence of predation on Neotropical birds have been intensively studied and documented, but identity of predators has largely remained unknown (Larivièreon factors affecting nest success and to understand the dynamics of predator-prey relationships (Benson et al. 2010). When predators have been documented, 1999, Lahti 2009). Knowledge of the identity of predators is often necessary to accurately focus conservation efforts for threatened species as well as to interpret results of researchFil: Berkunsky, Igor. Universidad Nacional del Centro de la Provincia de Bs.as.. Facultad de Cs.exactas. Instituto Multid.s/ecosistemas y Desarrollo Sustentable. Grupo de Ecologia Matematica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kacoliris, Federico Pablo. Un...
Patterns of Predation Risk and Survival of Bird Nests in a Chilean Agricultural Landscape
Conservation Biology, 2001
We used experimental nests baited with California Quail ( Callipepla californica ) eggs or clay eggs to examine relative risks of nest predation in an agricultural landscape and in two large forest preserves in a south-temperate rainforest in Chile. The most common predators, as identified by marks on clay eggs, were a caracara ( Milvago chimango ), a blackbird ( Curaeus curaeus ), and rodents. Nest losses from predation were similar in large and small forest patches and lower in patches than in extensive forest. In general, predation risk was higher (and nest survival therefore lower) on forest edges than in forest interior, in short-grass pasture than in tall-grass pasture, in narrow corridors than in wide corridors, and on visible nests than on concealed nests. High predation risks in pasture habitat tended to increase the risk of nest predation in adjacent forest edges. For open-cup nesters, the risk of nest predation was relatively high in the present agricultural landscape, indicating that much of the available wooded habitat ( forest edges, narrow corridors) offers poor nesting habitat, although it may be suitable for foraging and traveling. The numerous bird-plant mutualisms in this landscape may be at risk if nesting success of the principal mutualists is consistently low.
Artificial nest predation in natural and perturbed habitats of the central Monte Desert, Argentina
2004
We examined nest predation rates at artificial nests in two contrasting habitats (open woodland and shrubland) inside the Reserve of Ñ acuñán, west-central Argentina and in open woodlands within the reserve and a nearby grazed area, to assess whether between-habitat differences in vegetative structure were associated with changes in nest predation levels. We also quantified diurnal and nocturnal predation rates to further characterize the predator assemblage of the reserve. Nest predation rates and the estimated daily mortality rates were quite high in both open woodland and shrubland and did not differ significantly between them. Nest predation rate and daily mortality rate of nests in open woodlands of the reserve were high but similar to the rates for nests in adjacent grazed open woodlands. Nearly all predation events occurred during daylight hours. This result was not an artifact of the use of quail eggs because the proportion of depredated nests during the night was similar when we used smaller eggs of captive passerines. Our results support previous findings on the prevalence of birds as nest predators in this area. Avian predators seemed to be efficient at locating our artificial nests in all habitats, leading to the lack of differences between treatments. Conversely, our results suggest that extensive cattle grazing does not greatly modify nest predation risk for above-ground nests, although this conclusion is provisional given the conditions under which our experiments were carried out.
Edge effects reduce the nesting success of Acadian Flycatchers in a moderately fragmented forest
Journal of Field Ornithology, 2006
Forest fragmentation can create negative edge effects that reduce the reproductive success of birds nesting near the forest/nonforest interface, and threaten bird populations deeper in remnant forest habitats. Negative edge effects may be more pronounced in landscapes that are moderately fragmented, particularly where agriculture is the primary land-use fragmenting forests. Information about the extent and strength of edge effects at a site can help guide conservation actions, and determine their effectiveness. We examined edge effects for birds breeding in a nearly contiguous forest fragmented by relatively narrow agricultural corridors in Illinois (USA). We measured rates of nest predation and brood parasitism for Acadian Flycatchers (Empidonax virescens) over a continuum of distances from the edge of an agricultural inholding. Nest predation and brood parasitism were highest near the edge and decreased with increasing distance from the edge. Given the cumulative effects of nest predation and brood parasitism on reproductive success, we determined that forest within 600 m of the inholding was sink habitat. We found, however, that deeper forest interior areas currently serve as source habitat, and that conversion of the entire 205 ha agricultural corridor to forest would add 1350 ha of source habitat for Acadian Flycatchers. Such results provide support for a local conservation strategy of forest consolidation and establish baseline measures necessary to determine the relative effectiveness of any subsequent reforestation efforts. SINOPSIS. Efecto de borde reduce eléxito de anidamiento de Empidonax virescens en un bosque moderadamente fragmentado La fragmentación de bosques puede promover efectos negativos de borde que reducen eléxito reproductivo de las aves que anidan en la interfase bosque/no-bosque, amenazan las poblaciones de aves y las hacen anidar más profundo en el hábitat remanente. Los efectos negativos del borde pueden ser más marcados en paisajes moderadamente fragmentados, particularmente donde la agricultura, que es el uso primario de la tierra, produce la fragmentación. El obtener información sobre la extensión y fortaleza del efecto de borde en una localidad puede servir como guia para las actividades de conservación que se puedan llevar a cabo y determinar su efectividad. Investigamos el efecto de borde en aves que estaban reproduciéndose en un bosque fragmentado contiguo a un corredor agrícola en Illinois. Medimos la tasa de depredación y parasitismo reproductivo en un papamoscas (Empidonax virescens) a lo largo de un continuo de distancias desde el borde de un area agrícola. Tanto la depredación como el parasitismo fueron más altos cerca del borde y disminuyeron segun incremento la distancia del borde. Dado el efecto acumulativo de la depredación y el parasitismo reproductivo en eléxito de anidamiento, determinamos que elárea del bosque desde su comienzo hasta 600 m dentro de este era habitat detrimente. Nuestros resultados, sugieren que la parte más interior del bosque sirve como una buena fuente de habitat y que el convertir 205 ha de corredor agrícola en bosque añadiría 1350 ha adicionales de buen habitat para el papamoscas. Los resultados de este estudio proveen datos específicos que dan lugar a apoyar una estrategia de consolidación del bosque y de establecer medidas básicas necesarias para determinar la efectividad relativa de cualquier esfuerzo subsiguiente de reforestación.
Testing the importance of nest concealment: does timing matter?
Journal of Field Ornithology, 2009
Nest concealment by vegetation is considered an important factor affecting predation rates for many passerines and, therefore, is frequently measured in studies examining nest predation. However, the time when concealment measurements are made may affect the results of such studies, particularly in highly seasonal ecosystems where characteristics of the vegetation later in the breeding period may differ considerably from those at the time of nest-site selection. We used artificial nests baited with quail (Coturnix sp.) eggs in a highly seasonal tropical dry forest in Jalisco, western Mexico, to test the effects of seasonal change in concealment on nest predation.
Biological Conservation, 2002
Predation rates of artificial nests were investigated in a fragmented landscape in the lowlands of Los Tuxtlas in southern Mexico. Hen and plasticine eggs were used to assess predation pressure in four habitats: the interior of forest fragments, the forest-pasture edge, corridors of residual forest vegetation and linear strips of live fences across pastures. Three sites per habitat were used in three experimental trials. Hen and plasticine ground nests with three eggs each were alternated every 50 m along transects at each site. Predation rates on each type of nest were monitored for 9 days. Survey of potential avian and mammalian potential nest predators were conducted at each site prior to the experimental trails. Readings of amount of light illuminating the ground were taken by each nest at each site to assess exposure of nests. In general, average predation rates were significantly higher for both hen and plasticine nests in the forest-pasture edge and in the corridors than in the interior of the forest fragments. While birds and mammals were the principal predators on hen eggs in the forests, mammals were responsible for the majority (570%) of eggs damaged at the other habitats. Surveys of potential nest predators showed that avian and mammalian potential nest predators were significantly more common at the forest-pasture edges and at the other habitats than in the forests. Readings of light reaching the ground suggest that concealment of nests by the vegetation may play an important role in predation risk. Our results are consistent with reports from other Neotropical rainforests indicating an increase of artificial nest predation pressures from forest interior to open habitats. Restoration of forest fragments, allowing the vegetation to grow along the forest-pasture edge and the planting of arboreal crops at the forest-pasture edges may be measures that could increase cover and nest protection. #
Wind turbines do not negatively affect nest success in the Dickcissel ( Spiza americana )
The Auk, 2013
Proliferation of wind energy across the Great Plains of the United States has the potential to negatively affect many grassland birds through displacement, avoidance, or changes in nesting ecology. This is troublesome because grassland birds have had the highest average annual rate of decline over the past several decades. We studied the potential indirect effects of wind turbines on nesting success in Dickcissels (Spiza americana) at a utility-scale wind farm in north-central Texas in 2010 and 2011. We monitored 195 nests and found that proximity to a wind turbine did not affect nest density or nest-site characteristics. We used an informationtheoretic approach with logistic exposure modeling to identify the most likely models of nest fate. Nest initiation day and distance to wind turbine were the most important predictors of nest success. Proximity to a wind turbine did not reduce nest success. Furthermore, the daily survival rates at our site were within the range documented for Dickcissels at other sites without wind-energy developments. For the monitored nests, snake predation was the greatest source of nest failure and depredated nests were closer to woodland edges than to wind turbines. This may be because wind turbines were farther away from wooded edges. On the other hand, we cannot rule out the possibility that wind-energy development influenced predator behavior and activity, and this may warrant additional investigation. We recommend further research into the breeding ecology of a diverse selection of grassland species to fully assess the indirect effects of wind-energy development on grassland birds.
IS SELECTIVELY HARVESTED FOREST AN ECOLOGICAL TRAP FOR OLIVE-SIDED FLYCATCHERS?
The Condor, 2007
Disturbance-dependent species are assumed to benefit from forestry practices that mimic the appearance of postdisturbance landscapes. However, human activities that closely mimic the appearance but not the fundamental quality of natural habitats could attract animals to settle whether or not these habitats are suitable for their survival or reproduction. We examined habitat selection behavior and nest success of Olive-sided Flycatchers (Contopus cooperi) in a naturally occurring burned forest and an anthropogenically created habitat type-selectively harvested forest. Olive-sided Flycatcher density and nestling provisioning rates were greater in the selectively harvested landscape, whereas estimated nest success in selectively harvested forest was roughly half that found in naturally burned forest. Reduced nest success was probably a result of the relatively high abundance of nest predators found in the artificially disturbed forest. These results are consistent with the hypothesis that selectively harvested forest can act as an ''ecological trap'' by attracting Olive-sided Flycatchers to a relatively poor-quality habitat type. This highlights the importance of considering animal behavior in biodiversity conservation.
Conservation Biology, 1998
Many species of Neotropical migrant songbirds are experiencing population declines. Degradation of habitat on breeding grounds, particularly the fragmentation and isolation of forest habitats, has been suggested as an important factor in the decline of these populations. Using artificial ground nests containing quail and clay eggs, we compared risk of predation relative to the size of forest fragments, the proximity of nests to forest edge, and the density of nests. Because small predators rarely can damage or remove quail eggs, the loss of these eggs reveals activity by large predators. Small predators, however, often leave identifiable claw and tooth marks on artificial eggs, and we used such marks to assess the importance of small predators as nest predators. We found a negative correlation between predation rate and fragment size. Nest clustering increased predation by large predators but did not affect small predator activity. No significant edge effects on predation were apparent. The relative threat to nesting songbirds posed by small and large predators changed with forest fragmentation. Large predator activity increased as forests become more fragmented. Historically, interior forest-dwelling birds have been subjected primarily to small predator activity. The increased large predator activity we documented, against which songbirds have no defense, could be partially responsible for recent population declines.
Forest Fragmentation Increases Nest Predation in the Eurasian Treecreeper
Conservation Biology, 2004
Abstract: We used long-term breeding data to monitor the influences of fragmentation and habitat composition at different spatial scales on the reproductive success of Eurasian Treecreepers (Certhia familiaris) breeding in nest boxes. We collected data from the same forest patches (2.7–65.1 ha in size) during seven breeding seasons. Nest predation varied considerably over the years and was the primary cause of nesting failure (mean annual rate of 21.6 ± 12.8%). Nest predation explained most of the variation in fledgling production during the study period. Landscape-level fragmentation (radius of 500 m from territory center) affected nest predation more than did fragmentation on the territory scale (radius of 200 m from territory center). In general, nest loss due to predation in fragmented landscapes (32.4%) was almost threefold that of less fragmented (12.0%) landscapes. Of the habitat variables, predation rate correlated positively with the density of edges between forest and open land and with the proportion of sapling stands on the spatial scale of 500 m around a nest. In the core area of a territory (radius of 30 m from territory center), a high density of trees increased the frequency of nest predation. Further, a high proportion of agricultural land close to a nest site increased nest losses of treecreepers, probably because of a high degree of mustelid predation. Our results showed that the spatial scale on which we examined nest predation is important and that even within moderately fragmented landscapes it is possible to detect fragmentation-related nest predation.Resumen: Utilizamos datos de largo plazo para hacer un seguimiento de los efectos de la fragmentación y composición del hábitat en diferentes escalas espaciales sobre el éxito reproductivo de Certhia familiaris en nidos de cajón. Colectamos datos de los mismos parches de bosque (2.7–65.1 ha) durante siete épocas reproductivas. La depredación de nidos varió considerablemente a lo largo de los años y fue la causa principal del fracaso reproductivo (tasa media anual de 21.6 ± 12.8%). la depredación de nidos explicó la mayor variación en la producción de crías durante el período de estudio. La fragmentación a nivel de paisaje (radio de 500 m del centro del territorio) afectó a la depredación de nidos más que la fragmentación a escala de territorio (radio de 200 m del centro del territorio). En general, la pérdida de nidos debido a la depredación en paisajes fragmentados (32.4%) fue casi tres veces mayor que en los paisajes menos fragmentados (12%). De las variables de hábitat, la tasa de depredación se correlacionó positivamente con la densidad de los bordes entre el bosque y terrenos abiertos y con la proporción de árboles jóvenes en la escala espacial de 500 m alrededor de un nido. En el área núcleo de un territorio (radio de 30 m del centro del territorio), una alta densidad de árboles incrementó la frecuencia de depredación de nidos. Más aun, una alta proporción de terreno agrícola cercano a un nido incrementó las pérdidas de nidos, probablemente debido a un alto grado de depredación por mustélidos. Nuestros resultados mostraron que la escala espacial a la que examinamos la depredación de nidos es importante y que aun en paisajes moderadamente fragmentados es posible detectar la depredación de nidos relacionada con la fragmentación.Resumen: Utilizamos datos de largo plazo para hacer un seguimiento de los efectos de la fragmentación y composición del hábitat en diferentes escalas espaciales sobre el éxito reproductivo de Certhia familiaris en nidos de cajón. Colectamos datos de los mismos parches de bosque (2.7–65.1 ha) durante siete épocas reproductivas. La depredación de nidos varió considerablemente a lo largo de los años y fue la causa principal del fracaso reproductivo (tasa media anual de 21.6 ± 12.8%). la depredación de nidos explicó la mayor variación en la producción de crías durante el período de estudio. La fragmentación a nivel de paisaje (radio de 500 m del centro del territorio) afectó a la depredación de nidos más que la fragmentación a escala de territorio (radio de 200 m del centro del territorio). En general, la pérdida de nidos debido a la depredación en paisajes fragmentados (32.4%) fue casi tres veces mayor que en los paisajes menos fragmentados (12%). De las variables de hábitat, la tasa de depredación se correlacionó positivamente con la densidad de los bordes entre el bosque y terrenos abiertos y con la proporción de árboles jóvenes en la escala espacial de 500 m alrededor de un nido. En el área núcleo de un territorio (radio de 30 m del centro del territorio), una alta densidad de árboles incrementó la frecuencia de depredación de nidos. Más aun, una alta proporción de terreno agrícola cercano a un nido incrementó las pérdidas de nidos, probablemente debido a un alto grado de depredación por mustélidos. Nuestros resultados mostraron que la escala espacial a la que examinamos la depredación de nidos es importante y que aun en paisajes moderadamente fragmentados es posible detectar la depredación de nidos relacionada con la fragmentación.