Movements of Radio-Marked California Ridgway's Rails During Monitoring Surveys: Implications for Population Monitoring

2015 ◽  
Vol 6 (1) ◽  
pp. 227-237 ◽  
Author(s):  
Thuy-Vy D. Bui ◽  
John Y. Takekawa ◽  
Cory T. Overton ◽  
Emily R. Schultz ◽  
Joshua M. Hull ◽  
...  
Keyword(s):  
San Francisco ◽  
Bird Species ◽  
Population Monitoring ◽  
Tidal Marshes ◽  
Population Abundance ◽  
Population Declines ◽  
Directional Bias ◽  
Marsh Bird ◽  
Bird Monitoring ◽  
Count Surveys

Abstract The California Ridgway's rail Rallus obsoletus obsoletus (hereafter California rail) is a secretive marsh bird endemic to tidal marshes in the San Francisco Bay (hereafter bay) of California. The California rail has undergone significant range contraction and population declines due to a variety of factors, including predation and the degradation and loss of habitat. Call-count surveys, which include call playbacks, based on the standardized North American marsh bird monitoring protocol have been conducted throughout the bay since 2005 to monitor population size and distribution of the California rail. However, call-count surveys are difficult to evaluate for efficacy or accuracy. To measure the accuracy of call-count surveys and investigate whether radio-marked California rails moved in response to call-count surveys, we compared locations of radio-marked California rails collected at frequent intervals (15 min) to California rail detections recorded during call-count surveys conducted over the same time periods. Overall, 60% of radio-marked California rails within 200 m of observers were not detected during call-count surveys. Movements of radio-marked California rails showed no directional bias (P = 0.92) irrespective of whether or not playbacks of five marsh bird species (including the California rail) were broadcast from listening stations. Our findings suggest that playbacks of rail vocalizations do not consistently influence California rail movements during surveys. However, call-count surveys may underestimate California rail presence; therefore, caution should be used when relating raw numbers of call-count detections to population abundance.

scholarly journals Detection of local-scale population declines through optimized tidal marsh bird monitoring design

2020 ◽  
Vol 23 ◽  
pp. e01128
Author(s):  
Zachary S. Ladin ◽  
Whitney A. Wiest ◽  
Maureen D. Correll ◽  
Elizabeth L. Tymkiw ◽  
Meaghan Conway ◽  
...  
Keyword(s):  
Tidal Marsh ◽  
Local Scale ◽  
Population Declines ◽  
Marsh Bird ◽  
Monitoring Design ◽  
Scale Population ◽  
Bird Monitoring

Habitat openness and edge avoidance predict Saltmarsh Sparrow abundance better than habitat area

The Condor ◽  
2020 ◽  
Vol 122 (3) ◽  
Author(s):  
Hallie Marshall ◽  
Erik J Blomberg ◽  
Valerie Watson ◽  
Meaghan Conway ◽  
Jonathan B Cohen ◽  
...  
Keyword(s):  
Population Decline ◽  
Bird Species ◽  
Breeding Habitat ◽  
Tidal Marshes ◽  
Bird Abundance ◽  
Marsh Edge ◽  
Marsh Bird ◽  
Saltmarsh Sparrow ◽  
Habitat Features ◽  
Better Than

Abstract The Saltmarsh Sparrow (Ammospiza caudacuta) is a tidal marsh bird facing rapid population decline throughout its range, largely caused by degradation and loss of breeding habitat. Thus, there is a need to preserve tidal marshes in the northeastern United States, but to do so requires an understanding of the habitat features that support robust populations. Previous studies have shown Saltmarsh Sparrow abundance increases with marsh size, but in similar bird species, area sensitivity is more directly linked to edge avoidance. Whether additional landscape features affect the abundance of Saltmarsh Sparrows is unknown. We explored how the height of objects on the horizon, an index of habitat openness, affected the abundance of Saltmarsh Sparrows. Our primary goal was to determine whether the angle to the highest point on the horizon (“angle to maximum horizon”) predicted abundance better than marsh area or distance to the marsh edge. We used N-mixture models to evaluate the combination of spatial factors that best predicted Saltmarsh Sparrow abundance while also accounting for survey-level variables that could influence detection probability. We found that the interaction between distance to edge and angle to maximum horizon best predicted abundance. Taller objects on the horizon were negatively correlated with bird abundance, and this effect was strongest within 50 m of the marsh edge. When we considered the predictive powers of patch area, distance to edge, and angle to maximum horizon individually, angle to maximum horizon was the best single predictor. We found the highest abundance of Saltmarsh Sparrows at point locations where the angle to maximum horizon was 0.0°, and at angles greater than 12° the predicted abundance fell below 1 bird per survey point. We propose that managers should prioritize marsh openness and experimentally test the effect of marsh edge manipulations when making conservation decisions for this rapidly declining species.

Continuous population declines for specialist farmland birds 1987-2014 in Denmark indicates no halt in biodiversity loss in agricultural habitats

2017 ◽  
Vol 28 (2) ◽  
pp. 278-292 ◽  
Author(s):  
HENNING HELDBJERG ◽  
PETER SUNDE ◽  
ANTHONY DAVID FOX
Keyword(s):  
Bird Species ◽  
Biodiversity Loss ◽  
Population Declines ◽  
Farmland Birds ◽  
Long Distance ◽  
Breeding Bird ◽  
Specific Analysis ◽  
Bird Monitoring ◽  
Species Specific ◽  
Abundance And Distribution

SummaryThe 2020 EU biodiversity strategy aims to halt the loss of biodiversity and ecosystem services, but this requires effective monitoring to determine whether these aims are achieved. Common bird monitoring continuously assesses changes in the avian community, providing a powerful tool for monitoring temporal changes in the abundance and distribution of these upper trophic level consumers. Two-thirds of Denmark’s land area is intensively farmed, so agricultural habitats make a major contribution to Danish biodiversity. We looked for changes in abundance amongst farmland birds in Denmark during 1987–2014 to test for reductions in declines and to predict whether the 2020-target can be expected to be achieved. Sixteen specialist farmland species were those showing the most rapid declines amongst 102 common breeding species in Denmark. Of these, those species nesting on the ground showed significant long-term declines, which was not the case for those that nest elsewhere, i.e. in hedgerows, trees and buildings. There was no evidence to suggest that these trends were attributable to widespread declines in long-distance migrant species (as reported elsewhere), which may be affected by conditions at other times in the annual cycle. We therefore conclude that continued declines in specialist farmland breeding bird species are due to contemporary agricultural changes within Denmark and urge habitat- and species-specific analysis to identify the core causes of these changes and halt the declines.

scholarly journals Standardized North American Marsh Bird Monitoring Protocol

Waterbirds ◽  
2011 ◽  
Vol 34 (3) ◽  
pp. 319-346 ◽  
Author(s):  
Courtney J. Conway
Keyword(s):  
North American ◽  
Marsh Bird ◽  
Monitoring Protocol ◽  
Bird Monitoring

scholarly journals Hunting of migratory birds in North Sinai, Egypt

2015 ◽  
Vol 26 (1) ◽  
pp. 39-51 ◽  
Author(s):  
PERRI EASON ◽  
BASEM RABIA ◽  
OMAR ATTUM
Keyword(s):  
Migratory Birds ◽  
Bird Species ◽  
Migratory Bird ◽  
Mediterranean Coast ◽  
Population Declines ◽  
Mp3 Players ◽  
Southern Mediterranean ◽  
Sand Bar ◽  
North Sinai ◽  
Desert Scrub

SummaryDuring autumn migration, people set trammel nets along most of the Mediterranean coast of Egypt, with migrating Common Quail Coturnix coturnix as their primary target. These nets capture large numbers of quail, but also illegally capture other birds, which are then killed. We present the results of surveys from 2008 to 2012 along these lines of nets on the coast of North Sinai, Egypt. In desert scrub, which covers most of the Sinai coast, the mean number of quail killed reached a high of 357.1 per km per day in 2012, with a grand mean over the study period of 191.9 per km per day. Trammel nets also captured 54 other bird species in 28 families. Species captured at the highest rates in desert scrub included Corncrake Crex crex, Isabelline Wheatear Oenanthe isabellina and Greater Short-toed Lark Calandrella brachydactyla. Based on mean rates of capture from 2008 to 2012 in desert scrub and sand bar habitats, we estimate 2.0 million quail and 0.5 million birds of other species are killed annually in North Sinai during the 45 days of peak migration. In 2012, however, after the use of MP3 players to attract quail became widespread, we estimate that 3.3 million quail and 0.5 million other birds were captured. Hunters near the coast have recently begun covering shrubs and trees with mist nets to catch passerines. From 2010 to 2012, mist nets along our survey routes caught birds of 17 species in three families, with seven of these species caught only in this type of net. Hunting is likely to be a contributing factor to population declines for some species that migrate across Egypt and further studies of migratory bird hunting along the southern Mediterranean shore are badly needed.

scholarly journals Two Decades of Invasive Western Corn Rootworm Population Monitoring in Croatia

Insects ◽  
2018 ◽  
Vol 9 (4) ◽  
pp. 160 ◽  
Author(s):  
Martina Mrganić ◽  
Renata Bažok ◽  
Katarina Mikac ◽  
Hugo Benítez ◽  
Darija Lemic
Keyword(s):  
Adult Population ◽  
Monitoring Program ◽  
Population Monitoring ◽  
The United States ◽  
Western Corn Rootworm ◽  
Population Variation ◽  
Future Research ◽  
Corn Rootworm ◽  
Population Abundance ◽  
National Monitoring

Western corn rootworm (WCR) is the worst pest of maize in the United States, and since its spread through Europe, WCR is now recognized as the most serious pest affecting maize production. After the beetle’s first detection in Serbia in 1992, neighboring countries such as Croatia have established a national monitoring program. For more than two decades WCR adult population abundance and variability was monitored. With traditional density monitoring, more recent genetic monitoring, and the newest morphometric monitoring of WCR populations, Croatia possesses a great deal of knowledge about the beetle’s invasion process over time and space. Croatia’s position in Europe is unique as no other European nation has demonstrated such a detailed and complete understanding of an invasive insect. The combined use of traditional monitoring (attractant cards), which can be effectively used to predict population abundance, and modern monitoring procedures, such as population genetics and geometric morphometrics, has been effectively used to estimate inter- and intra-population variation. The combined application of traditional and modern monitoring techniques will enable more efficient control and management of WCR across Europe. This review summarizes the research on WCR in Croatia from when it was first detected in 1992 until 2018. An outline of future research needs is provided.

scholarly journals Are declines in insects and insectivorous birds related?

The Condor ◽  
2021 ◽  
Author(s):  
Douglas W Tallamy ◽  
W Gregory Shriver
Keyword(s):  
Plant Species ◽  
Invasive Plant ◽  
Bird Species ◽  
Insect Herbivores ◽  
Native Plant ◽  
Insectivorous Birds ◽  
Population Declines ◽  
Native Plant Species ◽  
Host Plant Specialization ◽  
Scale Population

Abstract A flurry of recently published studies indicates that both insects and birds have experienced wide-scale population declines in the last several decades. Curiously, whether insect and bird declines are causally linked has received little empirical attention. Here, we hypothesize that insect declines are an important factor contributing to the decline of insectivorous birds. We further suggest that insect populations essential to insectivorous birds decline whenever non-native lumber, ornamental, or invasive plant species replace native plant communities. We support our hypothesis by reviewing studies that show (1) due to host plant specialization, insect herbivores typically do poorly on non-native plants; (2) birds are often food limited; (3) populations of insectivorous bird species fluctuate with the supply of essential insect prey; (4) not all arthropod prey support bird reproduction equally well; and (5) terrestrial birds for which insects are an essential source of food have declined by 2.9 billion individuals over the last 50 years, while terrestrial birds that do not depend on insects during their life history have gained by 26.2 million individuals, a 111-fold difference. Understanding the consequences of insect declines, particularly as they affect charismatic animals like birds, may motivate land managers, homeowners, and restoration ecologists to take actions that reverse these declines by favoring the native plant species that support insect herbivores most productively.

scholarly journals Singing in the suburbs: point count surveys efficiently reveal habitat associations for nocturnal Orthoptera across an urban-to-rural gradient

2020 ◽  
Vol 24 (6) ◽  
pp. 1031-1043
Author(s):  
Darin J. McNeil ◽  
Christina M. Grozinger
Keyword(s):  
Site Occupancy ◽  
Habitat Associations ◽  
Survey Method ◽  
Population Declines ◽  
Detection Rates ◽  
Point Count ◽  
Point Counts ◽  
Focal Species ◽  
Habitat Gradient ◽  
Count Surveys

Abstract As evidence for global insect population declines continues to amass, several studies have indicated that Orthoptera (grasshoppers, crickets, and katydids) are among the most threatened insect groups. Understanding Orthoptera populations across large spatial extents requires efficient survey protocols, however, many previously established methods are expensive and/or labor-intensive. One survey method widely employed in wildlife biology, the aural point count, may work well for crickets and katydids (suborder: Ensifera) because males produce conspicuous, species-specific mating calls. We conducted repeated point count surveys across an urban-to-rural gradient in central Pennsylvania. Occupancy analyses of ten focal species indicated that, although detection probability rates varied by species from 0.43 to 0.98, detection rates compounded over five visits such that all focal species achieved cumulative > 0.90. Factors associated with site occupancy varied among species with some positively associated with urbanization (e.g., Greater Anglewing, Microcentrum rhombifolium), some negatively associated with urbanization (e.g., Sword-bearing Conehead, Neoconocephalus ensiger), and others exhibiting constant occupancy across a habitat gradient (e.g., Common True Katydid, Pterophylla camellifolia). Our community-level analysis revealed that different species’ habitat associations interacted such that intermediate levels of urbanization (i.e., suburbs) hosted the highest number of species. Implications for insect conservation Ultimately, our analyses clearly support the concept that aural point counts paired with static occupancy modeling can serve as an important tool for monitoring night-singing Orthoptera populations. Applications of point count surveys by both researchers and citizen scientists may improve our understanding Ensifera populations and help in the global conservation of these threatened insects.

scholarly journals Can Topographic Variation in Climate Buffer against Climate Change-Induced Population Declines in Northern Forest Birds?

Diversity ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 56 ◽  
Author(s):  
Raimo Virkkala ◽  
Juha Aalto ◽  
Risto K. Heikkinen ◽  
Ari Rajasärkkä ◽  
Saija Kuusela ◽  
...  
Keyword(s):  
Climate Change ◽  
Temperature Variation ◽  
Survey Data ◽  
Bird Species ◽  
Forest Birds ◽  
Local Temperature ◽  
Population Declines ◽  
Northern Forest ◽  
Bird Density ◽  
Topographic Variation

Increased attention is being paid to the ecological drivers and conservation measures which could mitigate climate change-induced pressures for species survival, potentially helping populations to remain in their present-day locations longer. One important buffering mechanism against climate change may be provided by the heterogeneity in topography and consequent local climate conditions. However, the buffering capacity of this topoclimate has so far been insufficiently studied based on empirical survey data across multiple sites and species. Here, we studied whether the fine-grained air temperature variation of protected areas (PAs) affects the population changes of declining northern forest bird species. Importantly to our study, in PAs harmful land use, such as logging, is not allowed, enabling the detection of the effects of temperature buffering, even at relatively moderate levels of topographic variation. Our survey data from 129 PAs located in the boreal zone in Finland show that the density of northern forest species was higher in topographically heterogeneous PAs than in topographically more homogeneous PAs. Moreover, local temperature variation had a significant effect on the density change of northern forest birds from 1981–1999 to 2000–2017, indicating that change in bird density was generally smaller in PAs with higher topographic variation. Thus, we found a clear buffering effect stemming from the local temperature variation of PAs in the population trends of northern forest birds.

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