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Wetlands in the Prairie Pothole Region (PPR) have experienced declines in areal cover, and many remaining wetlands are degraded. Recently, restoration of wetlands has been a key management strategy for waterbirds. In Iowa, the Department of Natural Resources and Ducks Unlimited, Inc. have restored 38 shallow lakes, which are large, mostly permanent wetlands. To assess the impact of habitat variables on migrant waterbird use (waterfowl, shorebirds, and secretive marsh birds), surveys were conducted at 19 shallow lakes restored 1 to 12 years prior to this study and at 11 soon-to-be-restored shallow lakes in Iowa during the spring of 2016-2018. A total of 713,338 waterbirds were identified in 82 species, and more waterbirds and species were detected at restored shallow lakes (582,148 waterbirds and 78 species) than at non-restored shallow lakes (130,895 waterbirds and 70 species). Greatest numbers of diving ducks and waterbird species occurred around 40-50% emergent cover. Water level negatively influenced dabbling ducks and shorebirds and positively influenced diving ducks and total waterbird abundance. Years-since-restoration positively influenced goose/swan abundance and secretive marsh bird abundance, and total wetland area had a positive effect on all groups. These findings emphasize how management strategies for restored shallow lakes should mimic the natural wet-dry cycle of prairie wetlands to provide benefits for all waterbirds.
Auditory callback is the standard method for monitoring rails and other secretive marsh birds that live in concealing habitats. Due to recent population declines, monitoring the King Rail (Rallus elegans) has become a conservation priority. Analysis of field recordings (n = 542 calls or notes) and behavioral observations were combined to provide an account of the structure and function of the King Rail's vocal repertoire, which included 10 different vocalizations. King Rails produced an array of pulsed sounds by altering frequency, note length, pulse rate, and amplitude of each call. The most commonly heard call, the grunt (61 calls recorded; 37 individuals), had multiple functions including mate communication, duetting, and interaction with neighbors in a ‘roll call’ context. The kek (208 calls; 46 individuals) was the primary mate advertisement call. Most of King Rail's calls, including alarms (165 notes; 7 individuals), screeches (47 calls; 7 individuals), churrs (43 calls; 10 individuals), and the poorly documented boom (5 calls; 5 individuals), were used and sometimes combined in defense and distress situations. Although previously described as a signal of receptivity by females, the kek-burr may also be used in the context of defense. This synthesis is intended to assist researchers and managers in interpreting behavioral observations and improving effectiveness of audio lures for detecting or trapping King Rails.
Wetland loss has increased the importance of multi-species management in remaining wetlands, which provide habitat for a multitude of wetland-dependent species. Many public wetlands across the mid-latitude United States are managed as moist soil impoundments with emphasis on migratory waterfowl. However, how the timing of these water management decisions affects rails is still uncertain. Wetland managers identified this as an area of uncertainty regarding timing of alternative water management strategies to benefit waterfowl and rails, which was addressed through a 3-year management experiment. Sora (Porzana carolina) and waterfowl were surveyed on 10 public wetland properties in Missouri, USA from 2014-2016, and their responses to early autumn inundation of managed palustrine wetlands were compared. A total of 558 Sora surveys detected 5,755 birds (20.6 birds/survey ± 30.8 SD), and 1,304 waterfowl surveys detected 1,411,779 birds (15,686.4 birds/survey ± 23,933.9 SD). Sora responded positively (birds/ha) to inundation of moist soil impoundments earlier in autumn migration (August). The top model for Sora included treatment, year and region of Missouri. There was no difference in waterfowl abundance between early or late inundation. Inundating wetlands earlier in autumn migration can provide habitat for migrating Sora without negative effects on waterfowl use of those wetlands, and wetland managers can incorporate this into their decision-making framework.
This study reports the effects of age and culling of breeding adults on movements and dispersal rates of Yellow-legged Gulls (Larus michahellis) from a western Mediterranean colony (the Medes Islands) based on recaptures and resightings of birds banded as chicks. Juveniles (1-year-old birds) were most frequently located in the French coast of Biscay and in the Western North Mediterranean. Older gulls became concentrated near the colony and its surroundings (core area), with 3rd year sub-adults and adults accounting for more than 70% and 90% of resightings in this area, respectively. Culling of breeding adults increased the dispersal rate of juveniles (pre-cull: 62.6% ± 6.0 SD; post-cull: 71.2% ± 6.4 SD) and mean distance of resightings of juveniles (pre-cull: 250.5 km ± 267.6 SD; post-cull: 367.6 km ± 300.1 SD), and favored displacement of juveniles to the French Atlantic coast. Culling also increased the dispersal rate of adults (pre-cull: 31.7% ± 16.6 SD; post-cull: 38.8% ± 16.3 SD) and mean distance of adult resightings (pre-cull: 27.4 km ± 108.7 SD; post-cull: 35.7 km ± 113.0 SD). This could be attributed to an increase in the number of gulls recruited to other colonies near the Medes Islands after culls. Culling performed in the Medes Islands colony seems to have effects at metapopulation level, conditioning the dynamics and management of other colonies.
In response to wetland degradation in the middle and lower reaches of Yangtze River floodplain, wintering waterbirds move to artificial wetlands. Exploring changes in behavior associated with habitat shifts can further understanding of waterbird adaptation to anthropogenic landscapes with frequent disturbances. In winter 2017–2018, vigilance patterns in Bean Goose (Anser fabalis) and White-fronted Goose (Anser albifrons) were quantified in natural and artificial habitats in Shengjin Lake, one of the typical Yangtze-connected lakes in China. No significant difference in percentage time spent vigilant between species was found, but vigilance frequency of White-fronted Goose was higher than Bean Goose. Percent time spent vigilant and mean scan durations in both species were higher in rice fields (Bean Goose: 15.3% ± 2.0 SE and 12.3 sec ± 1.6 SE; White-fronted Goose: 15.7% ± 2.8 SE and 8.6 sec ± 1.4 SE) than in natural wetlands (Bean Goose: 7.8% ± 1.9 SE and 5.7 sec ± 1.1 SE; White-fronted Goose: 9.8% ± 1.2 SE and 6.4 sec ± 0.7 SE), while no significant difference was found in vigilance frequency between the two habitats. Flock size was a negative predictor of the three vigilance components.
Eastern populations of Semipalmated Sandpipers (Calidris pusilla) have declined severely in recent decades, particularly at wintering grounds in northern South America, where about 80% of the population was lost since the 1980s. This study investigates prey choice of Semipalmated Sandpipers at two sites in major wintering grounds on the coast of Maranhão, northeast Brazil. Prey availability estimated from intertidal sediment samples was compared with bird diet reconstructed from prey remains in droppings. Birds (flocks of 80-90 birds) fed almost exclusively on the polychaete Laeonereis culveri (present in all droppings at both sites; ≥ 97% of total setae found in droppings), the most abundant invertebrate in the intertidal sediments overall, but they avoided the smallest sizes despite abundance in sediments and avoided numerous other species. Setae from two other polychaetes were found in droppings (Glycindes multidens, 53% of droppings; Hermondura tricuspis, 47% of droppings), but these represented < 2% in average of all setae in droppings. The disproportional prevalence of a single prey species in the diet of sandpipers in this study is comparable to well-studied stopover areas. High dependence on a single staple prey at different sites in the migration route can make Semipalmated Sandpipers vulnerable to changes in prey abundance, which may partly explain declines observed at the flyway level.
Assessments of possible adverse effects of transmitters on marked individuals is an important component of individual-based tracking studies, particularly for species that are listed under the U.S. Endangered Species Act. The breeding and post-breeding movements of adult Piping Plovers (Charadrius melodus) from the federally-threatened Atlantic Coast Population were studied by gluing miniature, 1.0-g, digital VHF radio-transmitters on their interscapular region. Mark-resighting data from 2015-2018 was used to estimate apparent survival rates for 289 adult Piping Plovers in Massachusetts, Rhode Island, and New Jersey in order to compare survival estimates between individuals with a transmitter attached and control individuals without a transmitter. Cormack–Jolly–Seber models were used for live-encounter data in a Bayesian framework to estimate apparent survival rates based on resightings of uniquely marked individuals. There was no evidence that mean apparent survival rates differed between adults with transmitters (0.756; 95% CI = 0.611 – 0.877) and without transmitters (0.673; 95% CI = 0.607 – 0.740). In addition, there was no evidence of differences in apparent survival rates between breeding location (state) or years. This study provides further evidence that radio transmitters glued temporarily to the inter-scapular region can be an effective tool to monitor local and regional movements of sensitive shorebirds, such as Piping Plovers.
King Rails (Rallus elegans) are a secretive marshbird often separated for management purposes into resident and migratory populations. The objective of this research was to gain a better understanding of where Midwest King Rails migrate and winter. Satellite transmitters were placed on nine King Rails captured in Ohio (USA). Autumn migration data was available for four individuals and spring migration data for two individuals. Autumn migration was completed in ≤ 5 days. During autumn migration, three individuals migrated from Ohio to the Gulf Coast, and one individual migrated from Pennsylvania to the southern Atlantic coast. Spring migration lasted longer and had more stopovers than autumn migration. During spring, one individual migrated from Louisiana to Indiana, and one individual migrated from Georgia to Louisiana, indicating likely immigration and emigration between coastal resident and Midwest King Rail populations. Departure dates from the breeding range varied from 30 August to 20 October and spring arrival date to the Upper Midwest was 20 April. All four of the individuals monitored were exposed to potential harvest while on the wintering range. We recommend continued satellite marking of the migratory population across their breeding range to improve understanding of the annual lifecycle of King Rail.
Royal Terns (Thalasseus maximus) and Cayenne Terns (Thalasseus sandvicensis eurygnathus) breed sympatrically in Patagonia, and very little is known about their breeding foraging patterns. Simultaneous information on the foraging patterns of both species using VHF radio-telemetry is presented from a mixed species colony in the Punta León Protected Area (43° 04′ S, 64° 29′ W), Chubut, Argentina. Transmitters were deployed on nesting adults of each species, which were tracked during the late incubation period between 21 November and 3 December 2006. In total, 101 locations of foraging terns were identified by means of radio-telemetry from the coast. Royal and Cayenne terns foraged primarily in waters less than 15 km offshore. Attenuation and lack of signal reception in some of these trips indicate that foraging also took place in waters further away, but in most cases along the coastline. Results indicate a different temporal pattern of nest departures between species. Royal Tern departure frequencies were not uniform, peaking around midday. In contrast, Cayenne Tern departure frequencies were higher around morning twilight, with lower peaks during early morning and evening twilight.
Double-crested Cormorant (Phalacrocorax auritus) populations have rapidly grown across the United States. In some locations cormorant populations have become a management concern due to real or perceived effects on local fish populations, altering island vegetation, and displacing other colonial waterbirds. In north-central Minnesota on Leech Lake cormorant populations have been reduced and managed by various removal and population reduction methods, which include fall nest material removal, lethal shooting, and limited harassment. These methods can be time intensive, costly, and can cause cormorants to disperse and renest. This study examines the use of artificial eggs as a new management method to reduce cormorant populations by limiting their fledging success. A portion of viable cormorant eggs from 68 nests were replaced and the nests monitored, and 32 nests were monitored as controls on an island nesting colony. Results demonstrate that cormorant fledging success is reduced by using artificial eggs. The average number of near fledge young per nest that received artificial eggs was 0.7 while control nests that did not receive artificial eggs had an average of 2.5 young per nest. Use of artificial eggs reduces cormorant fledging success and minimizes the chance of adults renesting elsewhere.
Current northward expansion of Ringed Kingfisher (Megaceryle torquata) and Green Kingfisher (Chloroceryle americana) into central Texas places them in aquatic systems with the temperate Belted Kingfisher (Megaceryle alcyon). Recent contact among the three species provides an opportunity to assess resource partitioning. A 23.5 km stretch of the South Llano River near Junction, Texas, USA was surveyed to determine seasonal abundance and compare foraging perch characteristics among the species. Data were collected on 7 foraging perch characteristics for 250 kingfisher observations across 26 surveys. Mean encounter rate for Green, Belted, and Ringed kingfishers per river kilometer was 0.48, 0.22, and 0.09, respectively. Green Kingfishers were present year-round, while the Belted and Ringed kingfishers were absent or rare from mid-spring to mid-summer. Characteristics of foraging perches were similar among the species with the exception of perch height, with Green Kingfisher having lower perches (142.3 cm ± 126.6 SD) than both Belted (550.8 cm ± 449.4 SD) and Ringed kingfishers (551.1 cm ± 422.7 SD). Mean perch heights of Green Kingfishers averaged higher during surveys when Belted Kingfishers were absent (210.5 cm ± 191.0 SD, n = 36) compared to surveys when Belted Kingfishers were present (124.0 cm ± 89.1 SD, n = 129).
This study documented the first breeding of Eastern Black Rails (Laterallus jamaicensis jamaicensis) in South Carolina, USA in more than a century. Previously, the only accepted nesting record in the state consisted of a single nest collected during 1903. Using motion-activated camera traps, we captured 942 photographs of Black Rails and documented Black Rail chicks during the summers of 2015 and 2016, and juveniles that were flightless, but nearly fully-feathered in 2016. Although, historically, Black Rails were considered to only be “accidental breeders” in the state, as population declines are documented in the Mid-Atlantic USA, coastal South Carolina may have increased importance within the breeding range.
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