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Winter ranges have been identified for most neotropical migrant bird species, those that spend the winter months in Central and South America and summer months in North America. Published accounts and specimen collections of the Northern Black Swift (Cypseloides niger borealis) during spring and fall migration are extremely limited and winter records are nonexistent. We placed light-level geolocators on four Black Swifts in August 2009, and retrieved three a year later. Data from the geolocators revealed initiation of fall migration (10 to 19 Sep 2009), arrival dates at wintering areas (28 Sep to 12 Oct 2009), departure dates from wintering areas (9 to 20 May 2010), and return dates to breeding sites (23 May to 18 Jun 2010) for Northern Black Swifts breeding in interior North America (Colorado, USA). Northern Black Swifts traveled 6,901 km from the Box Canyon breeding site and 7,025 km from Fulton Resurgence Cave to the center of the wintering area. The swifts traveled at an average speed of 341 km/day during the 2009 fall migration and an average speed of 393 km/day during the 2010 spring migration. This is the first evidence that western Brazil is the wintering area for a subset of the Northern Black Swift, extending the known winter distribution of this species to South America.
The duration of migration of the endangered Kirtland's Warbler (Setophaga kirtlandii) has not been previously documented. We estimated the average duration of spring migration for five male Kirtland's Warblers by observing uniquely color-banded individuals at or near both the beginning and end of spring migration in Eleuthera, The Bahamas, and Michigan, respectively. We estimated the average duration of spring migration for these five individuals to have been no more than 15.8 days (range 13–23 days) and the average distance traveled to have been 144.5 km/day (96.1–169.1 km/day).
We describe a new area of endemism for Amazonian birds which we designate as the Jaú Area of Endemism. This area of endemism in central-western Amazonia north of the Rio Solimões was identified through congruent distributions of six avian taxa: Psophia crepitans ochroptera Pelzeln 1857, Nonnula amaurocephala Chapman 1921, Pteroglossus azara azara Vieilot 1819, Picumnus lafresnayi pusillusPinto 1936, Synallaxis rutilans confinis Zimmer 1935, and Myrmoborus myotherinus ardesiacus Todd 1927. The southern and eastern limits of this area of endemism are the middle courses of the Solimões and Negro rivers, respectively. The northern limits apparently coincide with sandy soil vegetation along the middle Rio Negro. The western boundary remains undefined, but could involve the Japurá or Içá rivers north of the upper Solimões. Taxonomic studies and expansion of ornithological collections are needed to more precisely delimit the Jaú Area of Endemism. It is possible the avian taxa restricted to the Jaú Area of Endemism are derived through parapatric or peripatric speciation events from taxa whose ranges were centered in the Imeri and Napo areas of endemism. Alternatively, tectonic events that affect the lower course of the Rio Negro could influence bird distribution in this region if they serve as vicariance mechanisms.
We studied breeding season communities of grassland birds on short-grass and mixed-grass prairie sites during the second and third breeding seasons following two large wildfires in March 2006 in the Texas panhandle, USA. There was an apparent temporary shift in avian community composition following the fires due to species-specific shifts associated with life-history traits and vegetation preferences. Species that prefer sparse vegetation and bare ground on short-grass sites, such as Horned Lark (Eremophila alpestris), benefited from wildfires, while others, such as Western Meadowlark (Sturnella neglecta), that prefer more dense vegetation, were negatively impacted. Mixed-grass sites had species-specific shifts in 2007, two breeding seasons after the fires; grassland bird communities on burned plots were similar by 2008 to those on unburned plots. Avian communities appeared to return to pre-burn levels within 3 years following wildfires. Many of the responses in our study of wildfire were similar to those reported following prescribed fires elsewhere. Prescribed fires appear to have similar effects on the avian community despite differences in intensity and environmental conditions during wildfires.
We investigated the influence of arthropod abundance and vegetation structure on shifts in avian use of canopy gap, gap edge, and surrounding forest understory in a bottomland hardwood forest in the Upper Coastal Plain of South Carolina. We compared captures of foliage-gleaning birds among locations during four periods (spring migration, breeding, post-breeding, and fall migration). Foliage arthropod densities were greatest in the forest understory in all four seasons, but understory vegetation density was greatest in gaps. Foliage-gleaning bird abundance was positively associated with foliage-dwelling arthropods during the breeding (F = 18.5, P < 0.001) and post-breeding periods (F = 9.4, P = 0.004), and negatively associated with foliage-dwelling arthropods during fall migration (F = 5.4, P = 0.03). Relationships between birds and arthropods were inconsistent, but the arthropod prey base seemed to be least important during migratory periods. Conversely, bird captures were positively correlated with understory vegetation density during all four periods (P < 0.001). Our study suggests high bird abundance associated with canopy gaps during the non-breeding period resulted less from high arthropod food resource availability than from complex understory and midstory vegetation structure.
We describe the frequency of occurrence and seasonal variations of shorebirds (Charadriidae and Scolopacidae) along a 120-km transect of beach between Balneário Pinhal and Mostardas north of Lagoa do Peixe National Park, Rio Grande do Sul State over a 2-year period (Oct 2007 to Sep 2009). A total of 96,889 shorebirds was recorded. The greatest abundance occurred between October and April and the lowest occurred between May and September. The most abundant of the 17 species recorded were Sanderlings (Calidris alba), White-rumped Sandpipers (C. fuscicollis), and Red Knots (C. canutus). The least abundant were Semipalmated Sandpipers (C. pusilla), Rufous-chested Plovers (Charadrius modestus), and Hudsonian Godwits (Limosa haemastica). Fourteen species were migrants from the Northern Hemisphere, one was a migrant from the Southern Hemisphere, and two were residents. Nine species were recorded regularly, two were recorded sporadically, and six were recorded occasionally. Six Nearctic species were recorded in June and July most likely indicating the presence of non-breeding immatures. The beaches of Rio Grande do Sul are important migration stopover and wintering sites for many shorebirds in southern Brazil and should be a focus of conservation efforts, especially given the increasing development pressure that threatens these areas.
Environmental parameters in different breeding habitats of Red-backed Shrikes (Lanius collurio) in central Italy were examined at altitudes ranging from 0 to 1,200 m. The most suitable habitats for breeding were: (1) cultivated areas with hedgerows, and (2) high altitude grasslands. Similar population densities were recorded in both habitats (0.27 pairs/10 ha in farmland vs. 0.30 pairs/10 ha in meadows) and as were the number of fledged young per breeding pair (3.38 in farmland vs. 3.75 in meadows). The structural characteristics of ‘open space’ and ‘edge density’ differed in the two breeding habitats. Use of species of trees and bushes for nesting depended on habitat type, but nests were in the more abundant thorny shrubs (blackthorn [Prunus spinosa] in farmland and juniper [Juniperus communis] in meadows). Red-backed Shrikes in farmland appear to prefer to nest in the most heterogeneous territories, those with the presence of uncultivated areas and shrub patches. Plasticity of habitat selection by the species was evident.
The near-threatened Serra Finch (Embernagra longicauda) is restricted to the main mountain ranges in eastern Brazil inhabiting campos rupestres (rocky fields). We mapped 17 mated pairs in a 138-ha area within Serra do Cipó National Park; a density of 0.25 adults/ha. Estimated average territory size varied from 2.52 ± 0.77 ha (95% kernel) to 3.35 ± 0.90 ha (100% minimum convex polygon). The distance between territory centers of neighboring pairs was 162.38 ± 28.93 m. The overlap between neighboring territories was 15.3 ± 5.9% (95% kernel) and 2.0 ± 2.3% (polygon method). Pairs remained together throughout the year in the same territories and defended these against intruding neighbors. Analyses of habitat selection indicated preference for woodland and scrubland habitats associated with humid valleys, while grasslands were avoided. The Serra Finch used the available habitats more than expected from random at different spatial scales. Our data identified habitats that should be priority for conservation of the Serra Finch.
Drifting reefs of Sargassum (a brown alga) are used by a variety of pelagic seabirds in the western Atlantic Ocean. We examined gut contents from 964 individuals of 39 seabird species collected 5 to 60 km off the coast of North Carolina for evidence of Sargassum use. Sargassum pieces or Sargassum-associated prey were found in nine of 10 Procellariiformes species and less frequently among Charadriiformes (12 of 25 species). No Sargassum-associated prey was found in Pelecaniformes examined, but observational data indicated that Atlantic tropicbirds (Phaethon lepturus and P. aethereus) and Masked Boobies (Sula dactylatra) commonly foraged over Sargassum. Four species were considered Sargassum specialists, having frequencies of occurrence >25% and high volumes of Sargassum-associated prey: Audubon's Shearwater (Puffinus lherminieri), Royal Tern (Thalasseus maximus), Bridled Tern (Onychoprion anaethetus), and Red-necked Phalarope (Phalaropus lobatus). Seven species fed in Sargassum to a lesser extent, and nine species had ingested Sargassum pieces, but contained no Sargassum-associated prey. It is likely that other seabird species forage regularly over Sargassum, as our conclusions are based on relatively small sample sizes taken during random sampling in the open ocean. Our conservative analysis and extensive observational data indicate the Sargassum community is critical for feeding for some western North Atlantic seabirds. Degradation of Sargassum habitats by oil development, harvest, and/or ocean acidification would undoubtedly have negative effects on fitness of these birds.
We examined two critical predictions of the hypothesis that male Common Loons (Gavia immer) communicate greater aggressive motivation by increasing the number of repeat syllables within their territorial yodels. We observed (from >3,500 hrs of field observations of 58 males) the probability that territorial interactions escalated from territorial flyovers by intruders to stereotyped ‘social gatherings’ to escalated fights between residents and intruders was positively correlated to the number of repeat syllables given by individually-banded males. Males yodeling during these escalated contests often assumed the upright ‘vulture’ posture rather than the usual ‘crouch’ posture, reflecting an escalated aggressive motivational state. Territorial pairs responded sooner and with more threat and alarm vocalizations to playback yodels that contained more repeat phrases. This reflected a greater willingness to attack by residents to perceived intrusions by males of higher aggressive motivational state. Our study demonstrates the ability of loons to communicate greater aggressive motivation by lengthening acoustic territorial threat signals, which not only may be important for conveying imminent attack, but may also reflect important tactics for individuals of poorer fighting ability to deter territorial evictions. Our results also raise questions regarding what receiver-dependent and receiver-independent selective factors are responsible for maintaining signal honesty in this non-oscine bird.
We present the first record of territorial site-fidelity across multiple years by Purple-throated Caribs (Eulampis jugularis) on three different islands in the eastern Caribbean: St. Kitts, Dominica, and St. Vincent. Marked male Purple-throated Caribs were monitored throughout the flowering season of their main nectar resources, Heliconia caribaea (St. Kitts and Dominica) and H. bihai (St. Vincent), both native perennial herbs. Individual males were observed defending the same Heliconia patches for 3 years (St. Vincent), 4 years (St. Kitts), and 5 years (Dominica), and remained near these patches even when they were not in flower. The territorial behavior and resource dependence of Purple-throated Caribs on native heliconias likely have a key role in the coevolution of this specialized plant-pollinator interaction.
We monitored six flocks and five active nests of the Plush-crested Jay (Cyanocorax chrysops) at three sites in the Atlantic Forest in southern Brazil. The sites had different vegetation compositions and spanned different levels of anthropogenic disturbance. Home range size in fall/winter was 20–30 ha and the breeding territory size in spring/summer was 5–10 ha in size. Territories were smaller across sites with higher anthropogenic food supplementation. Flock sizes were 5–11 individuals during spring/summer and 8–15 individuals during fall/winter. The Plush-crested Jay is a cooperative breeder, nests were 4–7 m above ground level, the incubation period was 18-20 days, brood size (x¯ ± SD) was 3.4 ± 0.80 eggs per nest, and nestlings fledged 23 ± 1.26 days after hatching. This species occupies all forest strata but tends to use the understory and middle levels most (G = 178.2; P < 0.01). Invertebrates were the most frequently consumed item in all areas, but percent consumption varied among sites (G = 105.06; P < 0.01). We observed 110 food caching events throughout the year, primarily seeds of Araucaria angustifolia, maize, and coconuts. Caches were on the ground (n = 40), in epiphytes (n = 47), and on branches (n = 23). Levels of anthropogenic food supplementation resulted in variation in territory and home-range size, nestling survival rates, strata occupation, and diet composition of the Plush-crested Jay.
Little is known about mate selection and lek dynamics of Lesser Prairie-Chickens (Tympanuchus pallidicinctus). We collected data on male territory size and location on leks, behavior, and morphological characteristics and assessed the importance of these variables on male Lesser Prairie-Chicken mating success during spring 2008 and 2009 in the Texas Southern High Plains. We used discrete choice models and found that males that were less idle were chosen more often for mating. Our results also suggest that males with smaller territories obtained more copulations. Morphological characteristics were weaker predictors of male mating success. Peak female attendance at leks occurred during the 1-week interval starting 13 April during both years of study. Male prairie-chickens appear to make exploratory movements to, and from, leks early in the lekking season; 13 of 19 males banded early (23 Feb–13 Mar) in the lekking season departed the lek of capture and were not reobserved (11 yearlings, 2 adults). Thirty-three percent (range = 26–51%) of males on a lek mated (yearlings = 44%, adults = 20%) and males that were more active experienced greater mating success.
I examined the lek structure and behavior of male Plovercrests (Stephanoxis lalandi) at a lek in southern Brazil. The lek included seven territorial males; the distance between neighboring lek territories was 14.8 ± 6.3 m. Territory size was 11.4 ± 4.4 m2. Territory size and distance between territories were among the lowest reported for Trochilinae hummingbirds. Lek attendance by territory owners fluctuated throughout the day. Activity slowly diminished after an initial period of activity after arrival at sunrise, but increased again between 0900 and 1500 hrs. All males left their territories by 1830 hrs. Males sang at a similar rate (74.8 ± 14.5 songs/min) throughout the lekking season, but not throughout the day. There was no relationship between lek attendance and singing rate, two parameters that potentially affect mating success in lekking birds. Considerable interspecific variation occurs among lekking trochilines, indicating that much remains to be investigated about lek behavior and structure in hummingbirds.
We monitored Common Nighthawk (Chordeiles minor) nests in a managed grassland in the New Jersey Pine Barrens in 2009 and 2010, and assessed habitat selection by comparing vegetation characteristics at nests with random locations. We found relatively high nest survival with an estimated 79% chance of survival through incubation (daily survival rate = 0.987, n = 16 nests); predation was the most common cause of failure (n = 2). Movements of young (up to 45 m from the original nest site) were frequent, which introduced uncertainty that prevented us from estimating survival through fledging. Nest sites had significantly more open ground cover (e.g., sand, lichen) than random sites, as well as less shrub and grass cover, shallower litter, and lower mean vegetation height.
We describe reproductive traits of the Yellowish Pipit (Anthus lutescens) in the State of São Paulo, Brazil. We found 32 active nests during three breeding seasons (2008–2010). Domed nests were built exclusively on the ground where the grass was sufficiently tall to conceal them. Clutch initiation across years occurred from July to October and average ± SD clutch size was 3.05 ± 0.4 eggs or young. Yellowish Pipits were predominantly single-brooded. Eggs were pale white with brown spots and blotches that could be more concentrated at the larger end or homogeneously distributed over the entire surface. Eggs were 18.2 ± 0.8 mm in length, 13.7 ± 0.3 mm in width, and weighed 1.7 ± 0.12 g. Incubation and nestling periods lasted 13.03 ± 0.2 and 14.5 ± 1.0 days, respectively. Mean time incubating/hr was 38 ± 7.1 min, and incubation recesses averaged 9.4 ± 4 min. Young were provisioned on average 13.3 ± 7.9 times/hr, by both males and females. Estimated overall nesting success using a null model of constant nest survival rates was 87% (95% CI, 56–97%). Model selection analyses indicated survival was negatively correlated to nest age and time within the breeding season. Comparisons of Yellowish Pipit life history traits with northern temperate congeners provided support for the premises that clutch sizes are smaller and young development is slower in the tropics. The hypothesis that annual fecundity can be similar across latitudes due to a negative correlation between clutch size and number of renesting attempts was not supported. Our data contradicted the commonly claimed, but poorly tested hypothesis, that smaller clutch sizes in the tropics can be explained by a longer breeding season that permit more opportunities to renest within the same breeding season.
We monitored 256 Peregrine Falcon (Falco perigrinus) nest-sites, accumulating 852 site-years in Colorado, Wyoming, and Montana during 2005–2009. The sites included 42 selected by the U.S. Fish and Wildlife Service for its monitoring program in 2006 and 2009. Annual nest occupancy rates ranged from 75 to 100% and varied as much as 10% among years in each state, and 25% among states. Nest success was 77% overall (n = 687), but differed as much as 25% among states in 2009. Reproduction rate was 1.8 young/pair for 687 nesting attempts where outcome was known, and annual state averages ranged from 1.2 to 2.2 young/pair. We discovered or were alerted to 77 pairs at new locations, suggesting that future searches will be successful. Overall, 353 nesting locations in the three states combined had been recorded at the end of the 2009. Wide variations among years in occupancy, nest success, and reproduction underscore the necessity of long-term monitoring of Peregrine Falcons on a regional, rather than a state, perspective.
We describe the breeding biology and reproductive success of a Creamy-bellied Thrush (Turdus amaurochalinus) population from a southern temperate zone in western Argentina. We found 236 Creamy-bellied Thrush nests of which most were predated (67%). The breeding season was from late October to late December and clutch size was three eggs. Egg survival, hatching success, and fledgling survival of non-depredated nests were quite high (0.67 ± 0.03, 0.74 ± 0.03, and 0.87 ± 0.04, respectively). The number of eggs in the nest did not affect egg survival or hatching success, but number of nestlings in the nest affected fledgling success. Daily nest mortality was higher during the early and late nestling period than during laying, and early and late incubation periods. Highest nest mortality coincided with periods when activity of parents at the nest was highest. The clutch size was similar to data reported for thrushes from the tropics and south temperate areas, and lower than reported for thrushes from north temperate areas. This latitudinal pattern is similar to the general pattern described for passerines in the tropics and southern temperate areas.
We compared the red, green, and blue color values from digital photographs of the rictal flanges of nestling Brown-headed Cowbirds (Molothrus ater), a generalist obligate brood parasite, in sympatric Yellow Warbler (Setophaga petechia) and Song Sparrow (Melospiza melodia) nests at Mono Lake, California, USA. We detected significant differences in all three color components across nestlings of different species (R: P < 0.0001; G: P < 0.0001; B: P < 0.0001), but differences among cowbird nestlings from the nests of these two hosts were not significant (R: P = 0.543; G: P = 0.737; B: P = 0.319). Principal components results were mixed: Principal Component I described brightness and accounted for 84% of the variance. It did not differ among cowbird nestlings from nests of different hosts (P = 0.319). Principal Component II described chromaticity and accounted for 14% of the variance, which differed significantly among cowbird nestlings from the two different hosts' nests (P = 0.026). Color differences between cowbird nestlings from nests of different host species may result from selective parasitism by female parasites based on host nestling flange morphology, or ontogenetic effects on cowbird nestlings reared by different host species.
We identified natural pits associated with avian mortality at the base of Kiska Volcano in the western Aleutian Islands, Alaska in 2007. Living, moribund, and dead birds were regularly found at low spots in a canyon between two lava flows during 2001–2006, but the phenomenon was attributed to natural trapping and starvation of fledgling seabirds (mostly Least Auklets, Aethia pusilla) at a colony site with >1 million birds present. However, 302 birds of eight species, including passerines, were found dead at the site during 2007–2010, suggesting additional factors were involved. Most carcasses showed no signs of injury and concentrations of dead birds had accumulated in a few distinctive low pits in the canyon. Gas samples from these locations showed elevated CO2 concentrations in late 2010. Analysis of carcasses indicated no evidence of blunt trauma or internal bleeding. Volcanic gases accumulating at these poorly ventilated sites may have caused the observed mortality, but are temporally variable. Most auklets breeding in the Aleutian Islands do so in recent lava flows that provide breeding habitat; our study documents a cost of this unusual habitat selection.
The aerial arthropod prey of Neotropical Palm Swifts (Tachornis squamata) and Lesser Swallow-tailed Swifts (Panyptila cayennensis) in Venezuela included seven Orders and 60 families of insects plus spiders and mites. Diptera were the most numerous prey (>50%) taken by both swifts. Prey size ranged from 0.5 to 7.9 mm and averaged 2.43 and 2.77 mm, respectively. Both prey type and foraging habitat differences of these swifts could be interpreted as mechanisms for resource partitioning.
About 200 North American Eared Grebes (Podiceps nigricollis californicus) at Tule Lake Refuge in northern California were observed engaging in successive waves of mass pattering and pattering flights on 25 May 2011. Most grebes present in a part of a canal were involved in this activity. Counts of grebes on the morning of 26 May suggest an important portion of the Eared Grebes seen in pattering could have left the area over night. The behavior was characterized as zugunruhe. Directed mass pattering of Eared Grebes may contribute to synchronization of the onward migration of the birds involved.
The ‘Nest Protection Hypothesis’ suggests that some birds add aromatic plants to their nests to repel or kill ectoparasites. This behavior has been described for several species, including the Eurasian Blue Tit (Cyanistes caeruleus). We studied the reproductive performance, based on 26 nests (in nest boxes), of this species in mixed forested areas of Quercus spp. and Pinus pinea in the ‘Parque Florestal de Monsanto’, the largest park of Lisbon, Portugal. The frequency of aromatic plants in nests was compared with frequency of these plants in the study area. The three most frequent aromatic plants (Dittrichia viscosa, Lavandula dentata, Calamintha baetica) in nests were used more than expected from their availability in the study area. We could not reject the null hypothesis that nest survival rate is independent of the presence of aromatic plants in the nest.
We describe a nest and nesting activity of the Cinereous Warbling Finch (Poospiza cinerea) in Paredão da Serra do Curral City Park, Minas Gerais State in southeastern Brazil. Little is known about the reproductive biology of this globally vulnerable species. The nest was built with fragments of grass spikes in an Australian pine (Casuarina equisetifolia). The clutch consisted of three eggs. We describe courtship feeding behavior of the Cinereous Warbling Finch and brood parasitism of the nest by the Shiny Cowbird (Molothrus bonariensis).
We report the first nest of the Smoky Bush Tyrant (Myiotheretes fumigatus) which was found on 11 October 2009 at the Yanayacu Biological Station, Napo Province in Ecuador. The nest was a shallow open cup, 2 m above ground on the side of a dead stump covered in epiphytes. The nest was 12 cm wide by 6.5 cm in height; internally, the cup was 7 cm wide by 4 cm deep and was lined predominantly with scales from the tree-fern (Cyathea spp.), but included a few small sticks and brightly colored feathers. Both eggs were predominantly white with a few small, widely dispersed, dark reddish spots, predominantly around the fattest area. They measured 24.0 × 18 and 23.0 × 17.5 mm, and weighed 3.6 and 3.5 g, respectively. The first fully feathered fledgling left the nest on 2 November and the second on 3 November, for a nestling period of 16–17 days. We noted the presence of a third bird (besides the pair) which remained within the territory through the entire nesting period, at times in close association with the breeding pair.
We present the first detailed description of the nest and eggs of the Black-bellied Seedeater (Sporophila melanogaster) based on observation of 64 nests in three areas of grassland in southeastern Santa Catarina and northeastern Rio Grande do Sul states, Brazil. The nests were found from November through March. The nest has the shape of a shallow basket, constructed with portions of dried grasses and strung with spider webs. Half of the nests were constructed in Ludwigia sericea (Onagraceae), and the other half were in 15 other plant species. Of these, the most important were Eupatorium polystachyum (10%) and Achyrocline vauthieriana (6%) (Asteraceae). Only the female constructs the nest. The eggs are ovoid and colored whitish with brownish-purple spots near the wider portion. Clutch size was two eggs, rarely three.
We report the first nesting record of the Central American population of Brown Creeper (Certhia americana) in the La Montañona pine-oak (Pinus-Quercus) forest of Chalatenango Department, northern El Salvador. The nest was in a cavity in the trunk of a pine (Pinus oocarpa) tree. Most insectivorous birds in this region breed during the rainy season when insects are generally most abundant; however, nesting of the Brown Creeper occurred at the height of the dry season, during January and February.
Brood parasitism by Brown-headed Cowbirds (Molothrus ater) typically decreases the number of host juveniles that fledge: however, little information exists regarding the effect of cowbird parasitism during the post-fledging period. We monitored 115 Ovenbird (Seiurus aurocapilla) nests in 2006–2008 in northcentral Minnesota, six of which were parasitized. We used radiotelemetry to monitor movements of 36 Ovenbird fledglings (nine additional fledglings depredated <24 hrs after fledging were excluded from the movement analysis) from non-parasitized nests and one fledgling from a parasitized nest. Clutch sizes and productivity were lower in parasitized Ovenbird nests than non-parasitized nests, similar to populations at other locations. The fledgling we tracked from a parasitized nest (in 2008) died after 26 days. It was the only fledgling in our study that died (n = 20) with no sign of predation and an empty stomach. That fledgling took 12 days to travel >50 m from its nest and 25 days to travel >100 m from its nest. Fledglings from non-parasitized broods tracked for ≥25 days during 2008 (n = 16) took 4.1 ± 0.71 and 9.5 ± 1.14 days to travel the same distances. Our observations suggest that negative effects of brood parasitism may persist into the post-fledging period, possibly confirming observations of cowbird-only survival compiled from the literature.
We report the first observation of double brooding by Black-bellied Whistling-Ducks (Dendrocygna autumnalis). We monitored 151 nest boxes on the Rob and Bessie Welder Wildlife Refuge in south Texas during 1998 and 1999 and uniquely marked all incubating pairs of Black-bellied Whistling-Ducks using these nesting structures. We color-banded a pair of Black-bellied Whistling-Ducks in May 1999 that was incubating a clutch of 21 eggs, from which 18 young eventually fledged. The same pair later incubated a second clutch of 15 eggs in July and August 1999, of which 12 hatched. Double brooding is apparently not a common reproductive strategy for Black-bellied Whistling-Ducks in south Texas, but could be facilitated through biparental investment in most aspects of reproduction, including incubation and brood rearing, and a relatively long potential breeding season in most of this species' breeding range.
Production of a second brood, or double brooding, by a single female in one breeding season has not been reported for any species of grouse in North America. We describe the breeding history of one of 55 radio-marked female Greater Prairie-Chickens (Tympanuchus cupido) that successfully renested after losing a brood from a first nesting attempt during the 2011 breeding season in Kansas. Observations of double brooding by grouse might only be possible in areas like the Flint Hills of Kansas, where populations have a long breeding season in combination with a high rate of brood loss.
We report an apparent protective effect of neighboring Sora (Porzana carolina) nests on Red-winged Blackbird (Agelaius phoeniceus) nests in an experimental study. We suggest that quail eggs used in Sora nests acted as a supernormal stimulus drawing Marsh Wrens (Cistothorus palustris), the main predator in the system, from Red-winged Blackbird nests.