Showing papers in "The Wilson Journal of Ornithology in 2009"
420 citations
TL;DR: A suite of building characteristics that building designers can use to reduce risk of collisions by minimizing the proportion of glass to other building materials in new construction is recommended and it is suggested that reduction of reflective panes may offer increased protection for birds.
Abstract: We studied building characteristics and landscape context to predict risk of migratory birds being killed by colliding with sheet glass on Manhattan Island, New York City, New York, USA. Trained volunteers monitored 73 discrete building facades daily from the Upper East Side to the southern tip of the Island during autumn 2006 and spring 2007 bird migratory periods using a consistent and scientifically valid search protocol. We recorded 475 bird strikes in autumn 2006 and 74 in spring 2007 of which 82 and 85%, respectively, were fatal. Most building and context variables exerted moderate influence on risk of death by colliding with glass. We recommend a suite of building characteristics that building designers can use to reduce risk of collisions by minimizing the proportion of glass to other building materials in new construction. We suggest that reduction of reflective panes may offer increased protection for birds. Several context variables can reduce risk of death at glass by reducing ground cover, including changes in height of vegetation, and eliminating shrubs and trees from areas in front of buildings. We estimated 1.3 bird fatalities per ha per year; this rate extrapolates to 34 million annual glass victims in urban areas of North America north of Mexico during the fall and spring migratory periods. Clear and reflective sheet glass poses a universal hazard for birds, specifically for passage migrants in New York City, but also representative and comparable to growing urban areas world- wide. Received 21 May 2008. Accepted 14 August 2008.
85 citations
TL;DR: The Greater Ani (Crotophaga major) is the least well-known of the communally breeding crotophagine cuckoos, although it is locally abundant in Panama and northern South America.
Abstract: The Greater Ani (Crotophaga major) is the least well-known of the communally breeding crotophagine cuckoos, although it is locally abundant in Panama and northern South America. We present substantial new life history information from 87 breeding groups of Greater Anis at Gatun Lake, Panama, and the first description of their conspicuous, highly stereotyped communal displays. Breeding groups were composed of two to five socially monogamous pairs; no pairs nested singly. Seven groups also included an unpaired individual, which in three cases was confirmed to be a 1-year-old male from the previous year's nest. Groups of two and three pairs were most common (accounting for 75 and 20% of groups, respectively); groups containing more than three pairs were rare and their nests were abandoned before incubation began. Eggs were large (∼17% of adult body mass) and varied greatly in size (19–37 g). Egg and nestling development were exceptionally rapid: eggs were incubated for 11–12 days and nestlings were ...
53 citations
TL;DR: In this paper, the authors evaluated different methods to prevent collisions between birds and windows and found that window coverings with effective UV-reflecting and UV-absorbing patterns as warning signals can prevent unintentional killing of birds from collisions with windows.
Abstract: Birds behave as if clear and reflective glass and plastic windows are invisible, and annual avian mortality from collisions is estimated in the billions worldwide. Outdoor flight cage and field experiments were used to evaluate different methods to prevent collisions between birds and windows. Stripe and grid patterns of clear UV-reflecting and UV-absorbing window coverings presented an effective warning that birds avoid while offering little or no obstructed view for humans. Birds used UV-reflected signals to avoid space occupied by clear and reflective sheet glass and plastic. Window coverings with effective UV-reflecting and UV-absorbing patterns as warning signals can prevent unintentional killing of birds from collisions with windows. One-way films that made the outer surface of windows opaque or translucent were successful in deterring bird strikes. Ceramic frit glass consisting of a visual pattern of densely spaced 0.32-cm diameter dots, 0.32 cm apart was an effective collision deterrent. ...
51 citations
TL;DR: Kingbird nest defense is a repeatable behavior that differs between males and females and, as predicted by parental investment theory, nests of the greatest value (older young and earlier broods) were defended most aggressively.
Abstract: Nest defense represents a parental strategy to maximize fitness by enhancing prospects of offspring survival. We used a taxidermic mount of a nest predator to measure nest defense of Eastern Kingbirds (Tyrannus tyrannus) at Malheur National Wildlife Refuge in southeastern Oregon in 2003 and 2004 to test the hypotheses that intensity of nest defense (1) was individually repeatable, (2) differed between males and females, and (3) predicted nest success. We also predicted that (4) intensity of defense would increase with age and number of young, but decline over the breeding season. Intensity of nest defense was significantly repeatable for male kingbirds. Male response was twice as strong as female response during incubation and the nestling period, but nest success was independent of defense scores of males and females. Simple paired comparisons suggested female responses did not change between incubation and the nestling period, whereas males tended to defend nestlings more vigorously than eggs. ...
48 citations
TL;DR: The possible link between orientation-dependent differences in microclimate and hatching success, and the question of whether American Kestrels may select for orientation adaptively requires further investigation is studied.
Abstract: We studied orientation-dependent differences in nest box microclimate and American Kestrel (Falco sparverius) reproductive parameters in Idaho, USA. Unoccupied nest boxes facing west were ,0.6u C cooler than boxes that faced south or east and had ,20% lower relative humidity levels than boxes facing all other cardinal directions. Clutches in occupied boxes that faced southwest had a proportionately lower chance of hatching success (12 of 21 nests were successful), defined as having at least one egg hatch, than boxes that faced northwest (9 of 9 nests) or southeast (9 of 12 nests). The possible link between orientation-dependent differences in microclimate and hatching success, and the question of whether American Kestrels may select for orientation adaptively requires further investigation. Received 25 September 2008. Accepted 3 June 2009.
48 citations
TL;DR: Dispersal of plants by finches is probably more common than suggested by their predominant feeding patterns of seed predation and insectivory, and rare long-distance dispersal could be important for plant evolution and spread of introduced plants in the Galapagos Islands.
Abstract: We investigated seed predation and dispersal by nine Darwin's finch (Geospizinae) species, including species previously regarded as seed predators or insectivores. All nine ate fruit. Eight commonly discarded seeds, acting as short-distance dispersers. Seven defecated viable seeds, being therefore potential longer-distance dispersers. Fruit comprised the majority of dietary items in all four Geospiza species and Small Tree Finch (Camarhynchus parvulus). All except Common Cactus Finch (G. scandens) defecated intact seeds. The highest proportions of feces containing viable seeds were of Small Ground Finch (G. fuliginosa) and the “insectivorous” species Woodpecker Finch (Camarhynchus pallidus) and Warbler Finch (Certhidea olivacea). These two may be more important endochorous dispersers than other species that eat more fruit but are better seed predators. Intact seeds were found in 23% of fecal samples; 50% of the samples with intact seeds had viable seeds. The most frequently encountered intact see...
47 citations
47 citations
TL;DR: Conservation efforts to increase Northern Bobwhite reproductive success in southern New Jersey should focus on increasing the quantity of available breeding habitat.
Abstract: Northern Bobwhite (Colinus virginianus) populations have been declining throughout their range, but some of the sharpest declines have been documented in the Mid-Atlantic states. We conducted a 2 year (2006–2007) breeding season (1 May–30 Sep) telemetry study in southern New Jersey to collect baseline data on Northern Bobwhite reproductive rates, and nest and brood microhabitat selection. We located 23 Northern Bobwhite nests, of which 21 were usable for survival analyses. Incubation-period nest survival rate was 0.454 ± 0.010 (95% CI = 0.280–0.727). Mean clutch size was 14.2 ± 0.58 (range 10–19, n = 20) and hatching success was 96.1 ± 2.0% (range 86–100%, n = 10). The estimated probability that an individual that entered the breeding season would initiate incubation of ≥1 nest was 0.687 for females and 0.202 for males. Nest microhabitat selection was positively related to visual obstruction and percentage of litter. Brood microhabitat selection was positively related to visual obstruction,...
36 citations
TL;DR: The cost of “waiting” for a previous mate that might have died could be high in species with high annual mortality and the cost of switching boxes and mates were low, and there were no obvious benefits to fidelity.
Abstract: We assessed mate fidelity, nest-box fidelity, and breeding dispersal distances of American Kestrels (Falco sparverius) nesting in boxes in southwestern Idaho from 1990 through 2006. Seventy-seven percent of boxes had different males and 87% had different females where nest-box occupants were identified in consecutive years. High turnover rates were partly a result of box-switching. Forty-eight percent of males and 58% of females that nested within the study area in successive years used different boxes. The probability of changing boxes was unrelated to gender, nesting success in the prior year, or years of nesting experience. Breeding dispersal distances for birds that moved to different boxes averaged 2.2 km for males (max = 22 km) and 3.2 km for females (max = 32 km). Approximately 70% of birds that nested in consecutive years on the study area had a different mate in the second year. Mate fidelity was related to box fidelity but not to prior nesting success or years of nesting experience. Mat...
36 citations
TL;DR: It is estimated that 14.6% of breeding females were depredated on the nest during the breeding season based on the observed survival rates and assuming females whose first nest was unsuccessful and which survived attempted a second nesting attempt.
Abstract: We monitored 124 female Golden-cheeked Warblers (Dendroica chrysoparia) at 133 nests with video cameras from 1997–2002 and 2005– 2006 at two study areas in central Texas, USA. Six adult females were depredated by snakes in 781 camera-monitored intervals when females were on the nest at night and exposed to possible nocturnal predation. Daily nest survival was 0.971 (95% CI: 0.959–0.980) and daily adult female predation while nesting was 0.008 (95% CI: 0.003–0.017). We estimated that 14.6% of breeding females were depredated on the nest during the breeding season based on the observed survival rates and assuming females whose first nest was unsuccessful and which survived attempted a second nesting attempt. Females were captured 75% of the times they were on the nest at the time of a nocturnal nest predation by a snake. Predation of nesting females is potentially an important source of mortality for Golden-cheeked Warblers, and warrants further investigation.
TL;DR: Differences in the diet of Barn Owls among the three habitats most likely reflected differences in the distribution and abundance of the prey items in each habitat.
Abstract: We studied the diet of 20 Barn Owl (Tyto alba) pairs breeding in three habitats (alfalfa fields, date plantations, and villages) in the same agricultural region in the Jordan Valley, Israel Small mammals, particularly three rodents (Levant voles [Microtus socialis guentheri], house mouse [Mus sp], and Tristram's jird [Meriones tristrami tristrami]), comprised 73 to 88% of the 3,544 prey items taken by Barn Owls in the three habitats Frequencies in number and biomass of the rodent species differed among habitats The number of bird species, their frequencies, and biomass in the diet were higher in villages than in the other two habitats, and were related to the higher diversity of birds breeding in villages The frequency of birds in the diet was negatively correlated with distance from the village to open fields Differences in the diet of Barn Owls among the three habitats most likely reflected differences in the distribution and abundance of the prey items in each habitat
TL;DR: Most of the study species symmetrically replace flight feathers during the absence of migrant birds; molting during this period may limit resource competition during an energetically taxing phase of the avian life-cycle.
Abstract: Detailed accounts of molt and breeding cycles remain elusive for the majority of resident tropical bird species. We used data derived from a museum review and 12 years of banding data to infer breeding seasonality, molt patterns, and age and gender criteria for 27 common landbird species in northeastern Costa Rica. Prealternate molts appear to be rare, only occurring in one species (Sporophila corvina), while presupplemental molts were not detected. Most of our study species (70%) symmetrically replace flight feathers during the absence of migrant birds; molting during this period may limit resource competition during an energetically taxing phase of the avian life-cycle.
TL;DR: The diet of Military Macaws in tropical dry and oak forests of Cuicatlán, México was examined to identify diet composition, and nutritional content of all items which they consumed were quantified.
Abstract: The Military Macaw (Ara militaris) is an endangered species with a fragmented distribution and declining populations. Their diet has not been described in detail but the species is considered to be a specialized granivore, and individuals may make seasonal movements in search of food resources. This study examined the diet of Military Macaws in tropical dry and oak (Quercus spp.) forests of Cuicatlan, Mexico. We followed macaws to identify diet composition, and quantified the nutritional content of all items which they consumed. Military Macaws used 10 plant species during the year having a standardized Levin´s niche breath index of B = 0.18. Their diet consisted principally of seeds but also included fruits, leaves, and latex. Foods rich in protein and lipids composed the diet of macaws, especially during the breeding season. Macaws preferred some plant species using them more than predicted by their abundances. Food resources must be considered when managing and preserving habitat to protect th...
TL;DR: Tachycineta swallows nest in secondary cavities and build nests made of a mat of dry grasses with a nest cup lined with feathers, and Chilean Swallows make temporal adjustments to the number of feathers added to the nest, which may help maintain reproductive success throughout the breeding season.
Abstract: Tachycineta swallows nest in secondary cavities and build nests made of a mat of dry grasses with a nest cup lined with feathers. The insulative quality of feathers may prevent hypothermia of the chicks and increase chick growth, but also may raise the risk of nestling hyperthermia if ambient temperature is high. The number of feathers added to the nest should vary throughout the breeding season according to ambient temperature. We describe nest structure and timing of nest building of Chilean Swallows (Tachycineta meyeni) nesting in Tierra del Fuego, Argentina. We analyzed the association between number of feathers in the nest and (1) daily ambient temperature during the period swallows add feathers to the nest, and (2) hatching success of eggs and survival and growth of the chicks. There was a negative association between number of feathers added to the nest and average daily ambient temperature during the nesting cycle. Hatching success was not associated with number of feathers at start of la...
TL;DR: In this paper, the authors used 2 years of strip-transect surveys to evaluate avian density, richness, and conservation value between non-, narrow and wide field borders on intensive row-cropped field margins in the agriculture-dominated Mississippi Alluvial Valley.
Abstract: Avian communities can benefit from reconstructed herbaceous, strip habitats among agriculture; however, any benefits may be limited by width-dependent factors such as edge effects. We used 2 years of strip-transect surveys to evaluate avian density, richness, and conservation value between non-, narrow (mean width 5 8.2 m), and wide (mean width 5 40.7 m) field borders on intensive row-cropped field margins in the agriculture-dominated Mississippi Alluvial Valley. Wide field borders supported two times more birds (7.0 birds/0.2 ha) than narrow borders (3.6 birds/ 0.2 ha), which supported six times more birds than no border (0.6 birds/0.2 ha). Mean bird species richness was over five times greater in bordered (0.80-1.10 species/0.2 ha) than non-bordered margins (0.14 species/0.2 ha), but was largely uninfluenced by border width. We documented more bird use of agricultural fields and wooded fencerows adjacent to bordered than non-bordered margins. Red-winged Blackbirds (Agelaius phoeniceus) and Dickcissels (Spiza americana) had the strongest positive response to field border presence and width. Wide borders attracted high densities (2.0 birds/0.2 ha) of Dickcissels, an edge-sensitive species, suggesting the conservation potential of herbaceous vegetation patches ,50 m of wooded edges for grassland birds. Extensive implementation of field borders, particularly of enhanced width, may contribute substantially to grassland bird conservation strategies in intensive, agricultural landscapes, although confirmation of these benefits requires additional demographic information. Received 20 June 2008. Accepted 27 February 2009.
TL;DR: Prescribed fire may improve winter foraging conditions for this ground-dwelling species by reducing dense grass cover at ground level and increased flowering responses that many dominant plants exhibit following burns also may improveWinter food resources.
Abstract: Prescribed fire is used extensively to manage breeding habitat for Bachman's Sparrow (Aimophila aestivalis), but little is known about the effects of prescribed fire on winter habitat requirements We used conspecific recordings in conjunction with point counts to assess relationships between winter sparrow abundance and use of prescribed fire Counts of sparrows conducted over three winters were higher (059 ± 042) (x ± SD) when surrounding vegetation was burned the previous breeding season than in areas burned >18 months earlier (027 ± 038) Year-to-year abundance estimates for individual stations increased an average of 039 (± 054) individuals per count when surrounding vegetation was burned the previous breeding season and decreased 022 (± 059) individuals per count when vegetation was not burned Sparrow counts were positively correlated with percent bare ground cover surrounding census stations and negatively correlated with increases in percent grass cover, grass standing crop, hei
TL;DR: The results indicate Yellow-rumped Warblers may have an advantage over long-distance migrants in view of global climate change as they can arrive early at stopover habitats and exploit resources when they are most available.
Abstract: I examined the temporal pattern of migration and tree species preferences of Yellow-rumped Warblers (Dendroica coronata) in relation to tree and food phenology across three spring seasons (2001–2003) at a migration stopover site in east-central Illinois, USA. Foraging Yellow-rumped Warblers used tree species in relation to the date that trees initiated bud break and the date caterpillars were most abundant in trees. The first arrival date of Yellow–rumped Warblers at the stopover site varied with date of bud break; duration of migration through the stopover site ranged from 31 to 47 days. The earliest Yellow-rumped Warbler migrants observed arrived at the stopover site before appearance of many arthropods, and foraged on the temporarily abundant adult stage of the hackberry psyllid (Pachypsylla spp. [Fletcher] [Homoptera]). Later migrants switched to foraging for caterpillars. The proportions of foraging observations among tree species were similar across all 3 years and, each year, tree species ...
TL;DR: Management that protects both the shrub and herbaceous component of the shinnery oak community is essential for maintaining nesting habitat for Lesser Prairie-Chickens in east-central New Mexico.
Abstract: I evaluated the effects of habitat composition on Lesser-Prairie-Chicken (Tympanuchus pallidicinctus) breeding season habitat use in shinnery oak (Quercus havardii)-dominated rangelands. Female Lesser Prairie-Chickens selected nest sites with greater visual obstruction, shrub height, shrub cover, and litter compared to adjacent rangeland sites with most (n = 21) selecting nest sites within 1 km of the leks on which they were captured. Successful nests were in areas with greater visual obstruction and were characterized by greater canopy cover of shrubs than at unsuccessful nests. Nesting habitat did not appear to be limited on the study area and use of shinnery oak-dominated rangelands did not reflect poor or scarce nesting habitat. Management that protects both the shrub and herbaceous component of the shinnery oak community is essential for maintaining nesting habitat for Lesser Prairie-Chickens in east-central New Mexico.
TL;DR: The female-larger size dimorphism of Peruvian Boobies is intermediate in comparison to other Sula boobies and calls and biometry provide a fast, reliable, and inexpensive method for classifying most adult PeruvianBoobies as males or females in the field.
Abstract: We studied adult Peruvian Boobies (Sula variegata) on two islands in northern Peru to classify males and females using DNA-based techniques We used this information to (1) assess the extent of size dimorphism in this species, (2) identify males and females using discriminant functions of external characters, and (3) validate use of voice as a reliable method for identifying male and female Peruvian Boobies in the field Female Peruvian Boobies were 19% heavier and their culmens and wings were 3 and 4% larger than males, respectively A discriminant function that included body weight and wing chord correctly classified 90% of the birds Alternatively, 88% of correct identification of males and females was obtained with a function that incorporated only wing chord Whistles were performed exclusively by males (25/25 of cases), whereas grunts or goose-like honk vocalizations were performed only by females (24/24 of cases) The female-larger size dimorphism of Peruvian Boobies is intermediate in comparison to other Sula boobies Calls and biometry provide a fast, reliable, and inexpensive method for classifying most adult Peruvian Boobies as males or females in the field We recommend a hierarchical system for classification of male and female Peruvian Boobies: (1) use of vocalizations, (2) use of body weight and wing chord when the bird did not vocalize and was weighed immediately after daybreak or before the first feeding trip of the day, and (3) use of wing chord only when there is uncertainty in temporal variations of body weight
TL;DR: The status of Laysan Albatross populations at Kaena Point and Kuaokala on the island of Oahu, Hawaii is reported and new demographic data for this species is provided, indicating these colonies may serve as refugia in the event of sea level rise and, thus, should continue to be conservation priorities.
Abstract: Laysan Albatross (Phoebastria immutabilis) began re-colonizing sites across the Pacific in the 1970s after severe population declines, and fledged the first chick on the island of Oahu in 1992. We report the status of Laysan Albatross populations at Kaena Point and Kuaokala on the island of Oahu, Hawaii and provide new demographic data for this species. Colonies on Oahu were monitored weekly from 2004 to 2008; all individuals were censused, banded, and genetically identified to gender. There was a population of 365 adults on Oahu in 2008 of which 47% were active breeders. The breeding population increased 27% annually since 1991. The high rate of increase was due primarily to immigration with some local recruitment. Recaptures indicate that seven birds were from French Frigate Shoals, one was from Midway Atoll, and 52 were from Oahu and returning to breed; all other adults were of unknown origin. Hatching rate (62%), fledging rate (78%), and overall reproductive success (48%) were comparable to o...
TL;DR: Vocal similarities between two species not normally grouped together (Cassin's and Parakeet auklets); and Whiskered and Crested auklet, which have been suggested previously to be closely related are revealed.
Abstract: We categorized and quantified the complete vocal repertoires of breeding adult auklets (Aethiini, 5 species) in their breeding areas to provide a baseline for comparative study of the structure and function of vocalizations within this monophyletic group of seabirds. We recognized 22 call types across species and 3–5 call types for each species. Calls were characterized by one to five frequency modulated, harmonically rich note types arranged sequentially in varied combinations. Frequency attributes varied more than temporal attributes within and across species. Repertoires and display complexity of nocturnal and diurnal species did not differ consistently. We recognized two major forms of vocal display: alternating arrangement of note types (Cassin's Auklet [Ptychoramphus aleuticus] and Parakeet Auklet [Aethia psittacula]); and sequentially graded arrangement of note types (Least Auklet [A. pusilla] and Whiskered Auklet [A. pygmaea]). One species' repertoire (Crested Auklet [A. cristatella]) was...
TL;DR: Habitat used for nesting on the Wisconsin study areas may be less important for survivorship and lifetime reproduction than acquisition of a nesting area in which a male will breed throughout his life.
Abstract: There are few published data on annual survival and no reports of lifetime reproduction for breeding Cooper's Hawks (Accipiter cooperii). Breeding males (n = 105) in central and southeastern Wisconsin had an annual mortality rate of 19%, or a survival rate of 81% for birds ≤10 years of age. We did not detect significant differences in mortality rates between urban and rural habitats, nor between the earlier 13 years and later 13 years of this study. Male Cooper's Hawks produced from zero to 32 nestlings during their lifetimes. Body mass or size appeared unrelated to annual survivorship and lifetime reproduction, although lifetime reproduction was correlated strongly with longevity of breeding males. Fifteen of 66 males (23%) produced most (53%) of the nestlings. Our studies occurred in an area where breeding populations may be increasing with some of the highest reported productivity indices and nesting densities for this species. Habitat used for nesting on our Wisconsin study areas may be les...
TL;DR: Within-song variation may be an important way to vary song meaning for male Blue Grosbeaks, and perhaps other males in species with a single song type but repertoires of several different song elements.
Abstract: Songs of individual male Blue Grosbeaks (Passerina caerulea) typically begin with the same combination of elements, but the sequence and number of elements in the latter portion of songs vary. We examined the possible functions of within-song variation in Blue Grosbeaks at the Blue Grass Army Depot near Richmond, Kentucky, USA from 15 April to 31 July 2007. We examined singing rates and song characteristics of second-year (SY; n 5 6) and after-second-year (ASY; n 5 14) males, and conducted playback experiments (n 5 15) to identify the possible function of variation in song length. Male Blue Grosbeaks sang at highest rates prior to pairing, maintained relatively high singing rates during the post-pairing/pre-nesting and nest-building/egg-laying stages, and sang at lower rates during the incubation, nestling, and fledgling stages. These results suggest high singing rates are important in attracting mates and establishing territories, and lower singing rates may result from trade-offs associated with parental care. Males used longer songs during aggressive encounters with conspecifics and responded more aggressively to playback of longer songs. This suggests songs containing more elements signal increased aggression. Within-song variation may be an important way to vary song meaning for male Blue Grosbeaks, and perhaps other males in species with a single song type but repertoires of several different song elements. Received 13 February 2009. Accepted 17 June 2009. Singing by male songbirds serves a variety of functions, ranging from establishing territories and attracting mates (Smith 1991) to distracting predators (Ritchison 1991), communicating with young (Beecher 1990), coordinating nest ex- changes with mates (Smith 1988), and informing
TL;DR: Attentiveness, mean Tegg, and number of minutes Tegg reached their highest values 1 day or night after clutch completion, and Western Bluebirds exhibit gradual onset to incubation that is attributable to vagaries of weather and varying patterns of parental attentiveness.
Abstract: We present the first detailed information on egg laying, egg temperature (Tegg), and development of attentiveness and incubation in Western Bluebirds (Sialia mexicana). We used miniature infrared CCD video cameras to record egg laying at three nest boxes and validate attentiveness measurements derived from Tegg in seven other nests. Females entered the nest box on egg-laying days between 0522 and 1037 hrs PST and laid an egg on average 11.4 6 4.3 min later (n 5 11). Warm weather early in egg laying often elevated Tegg above physiological zero (27u C), despite low parental attendance. Females often began roosting in the nest box 2-3 nights before clutch completion, and most birds began steady night-time incubation with the penultimate egg. Attentiveness, mean Tegg, and number of minutes Tegg exceeded 27u C reached their highest values 1 day or night after clutch completion. Western Bluebirds exhibit gradual onset to incubation that is attributable to vagaries of weather and varying patterns of parental attentiveness. Received 8 September 2008. Accepted 10 February 2009.
TL;DR: The literature review indicates parulids differ strongly in life histories between temperate and tropical/subtropical sites with species in the tropics having, on average, smaller clutches, longer incubation periods, lower nest attentiveness, longer off-bouts, and longer nestling periods.
Abstract: We document reproductive life history traits of the Three-striped Warbler (Basileuterus tristriatus) from 146 nests in Venezuela and compare our results to data from the literature for other tropical and temperate parulid species. Mean (± SE) clutch size was 1.96 ± 0.03 eggs (n = 96) and fresh egg mass was 2.09 ± 0.02 g. The incubation period was 15.8 ± 0.2 days (n = 23) and the nestling period was 10.5 ± 0.3 days (n = 12). Males did not incubate and rarely provided food for females during incubation. Females had 57 ± 2% (n = 49) nest attentiveness (% of time on the nest incubating), which caused egg temperature to commonly become cold relative to development. Both adults fed nestlings and feeding rates increased with nestling age. The growth rate constant for nestlings based on mass was K = 0.490, which is slower than for north temperate warblers. Predation was the primary source of nest failure and only 22% of nests were successful based on a Mayfield daily predation rate of 0.048 ± 0...
TL;DR: In this paper, the authors used available published data to compare composition and richness of cavity adopters and cavity excavators across seven forest localities in Costa Rica and found that the abundance of wood cavities is a limiting factor for bird species that depend on these cavities for nesting.
Abstract: The abundance of wood cavities is thought to be a limiting factor for bird species that depend on these cavities for nesting. Thus, it is expected that number of cavity adopters correlates with number of cavity excavators across communities. We used available published data to compare composition and richness of cavity adopters and cavity excavators across seven forest localities in Costa Rica. Species richness and composition of cavity excavator and cavity adopter bird assemblages varied among the seven forests. Species composition of excavators and adopters was more similar between nearby localities and between localities with similar forest types. Richness of wood-cavity adopters (using mostly cavities created by excavators) tended to increase with richness of excavators. The lack of association between cavity adopters and cavity excavators in some localities may be compensated by high abundance of a few species of excavators. The abundance of adopters and their dependence on forested habitats...
TL;DR: The first description of the nest, eggs, and nestlings of the Planalto Woodcreeper (Dendrocolaptes platyrostris), a secondary cavity-nester, based on three nests in natural cavities and 14 in nest boxes is provided.
Abstract: We provide the first description of the nest, eggs, and nestlings of the Planalto Woodcreeper (Dendrocolaptes platyrostris), a secondary cavity-nester, based on three nests in natural cavities and 14 in nest boxes. Nests were found from October to January in 1997, 2006, and 2007 in the humid Chaco and Atlantic Forest of Argentina. Planalto Woodcreepers used natural cavities and nest boxes 40–60 cm deep with entrance diameters of 5–12 cm. They selected the deepest nest boxes available. Three or four white eggs were laid on a bed of bark flakes and incubated for 14–16 days. Newly hatched nestlings had pink skin with gray down, yellow mouth linings, and large whitish gape flanges. They opened their eyes when 6–7 days of age and fledged at 16–18 days. Nearly all nestlings were infested with botflies (Philornis sp.). Both adults contributed to nest building, incubation, nestling-rearing, and nest sanitation.
TL;DR: Nocturnal migration is accompanied by sleep loss likely dependent upon the length of the migratory flight, and migrants may minimize the effect of sleep deficit by inserting brief naps into their daytime activities.
Abstract: Nocturnal migration is accompanied by sleep loss likely dependent upon the length of the migratory flight. Migrants may minimize the effect of sleep deficit by inserting brief naps into their daytime activities. On 25 April 2006, I observed daytime sleep-like behavior by a radio-marked male Hooded Warbler (Wilsonia citrina) at a coastal stopover site in southwestern Louisiana. The bird likely completed a flight across the Gulf of Mexico a few hours before the observation and departed from the stopover site the evening of the day of arrival. To my knowledge, this is the first reported field observation of daytime sleep behavior in a neotropical landbird migrant. The behavior exhibited in the field was consistent with behavioral characteristics of daytime sleep observed in captive migrants.
TL;DR: This work quantifies the first records of winter site fidelity for Gray Catbird, House Wren, and Orange-crowned Warbler, and documents the first known winter returns of Blue-headed Vireo and Ovenbird in temperate winter areas.
Abstract: Many species of temperate migrant birds are abundant in winter in the southeastern United States, but little is known about fidelity of migratory species to wintering areas. Mist netting was conducted at Rock Springs Run State Reserve in Orange County, Florida during the non-breeding season from 1997 to 2002. We quantify the first records of winter site fidelity for Gray Catbird (Dumetella carolinensis), House Wren (Troglodytes aedon), and Orange-crowned Warbler (Vermivora celata). We also document the first known winter returns of Blue-headed Vireo (Vireo solitarius) and Ovenbird (Seiurus aurocapilla) in temperate winter areas. Many site faithful birds exhibited over-winter site persistence by being recaptured many times throughout the winter (over 4 weeks), suggesting these birds are site faithful within and between years. Patterns of returns and over-winter site persistence followed trends expected from life history characteristics for most species.