Breeding ecology of White-faced Ibis ( Pleagadis chihi ) in the Upper Klamath Basin, California

The White-faced Ibis ( Plegadis chihi ) is a California state and U.S. Fish and Wildlife Service species of special management concern. We studied White-faced Ibis breeding ecology from May through July 1995 on Lower Klamath National Wildlife Refuge (NWR) in the upper Klamath Basin of California. A total of 2029 pairs nested in 3 colonies exclusively in early-successional hardstem bulrush ( Scirpus acutus ). Nest initiation dates ranged from 10 May to 12 June, and mean clutch size was 3.16. Reproductive success averaged 87% apparent nest success ( n = 115), 82% hatchability, 97% whole and partial brood survival, and 2.39 fledglings per successful nest. Mayfield estimates of nest survival were 79.1% during the laying and incubation period and 95% during the nestling period. Overall nest success as estimated by the Mayfield method was 75.4%. Our estimates of nest success are some of the highest reported anywhere in the literature for White-faced Ibis. Therefore, Lower Klamath NWR may maintain preferred White-faced Ibis breeding habitats in years of otherwise poor habitat conditions across the Intermountain West.     

Breeding in the gray-headed tody-flycatcher (Aves: Tyrannidae) with comments on geographical variation in reproductive traits within the genus Todirostrum

The gray-headed tody-flycatcher Todirostrum poliocephalum is a passerine endemic to the Atlantic Forest of Brazil. We describe the nest and nesting behaviour of this species and investigate geographical variation in breeding traits in the genus using data from the literature, museum collections, and citizen science projects. We located 21 nests of the gray-headed tody-flycatcher, 13 of which we monitored. Nest height above the ground averaged 3.3 ± 3.4 m (n = 21). Nests were built over a 16.8 ± 5.6-day period (n = 6) by both adults. Clutch sizes ranged from two to three eggs, with a mean of 2.9 ± 0.3 eggs (n = 10). Eggs measured 16.6 ± 0.5 × 12.0 ± 0.5 mm (n = 23) and weighed 1.1 ± 0.1 g (n = 19). Mean incubation period was 17 days (n = 3) and mean nestling period was 15.5 days (n = 2). Apparent reproductive success was 30.8%, with predation being the primary cause of nest failure (46.1%). Mayfield’s reproductive success was 25.9%, and daily survival rates for eggs and nestlings were 0.957 and 0.971, respectively. Clutch sizes increased with latitude, but temperature and precipitation seasonality had very low importance in explaining clutch size variation.     

Breeding biology of the Sayaca Tanager (Thraupis sayaca) in southeast Brazil

ABSTRACT

Thraupis is a genus of the American endemic Thraupidae (subfamily Thraupinae), comprising seven species that inhabit tropical forests to urban centres. The Sayaca Tanager (Thraupis sayaca) is a disturbance-tolerant species of high representativeness in plant-frugivore networks, but information on its breeding biology is scarce and often restricted to non-systematic surveys. We studied the breeding biology of the T. sayaca, following 39 active nests in a periurban area of southeast Brazil during two breeding seasons (2017/2018, 2018/2019). The breeding season ranged from early September to middle December, and the nests were placed in native and exotic plants and human buildings (nest height above ground: 3.35 ± 1.73 m, mean ± SD). Only females incubated and brooded, but both adults built the nests, fed the nestlings, and removed their faecal sacs. Clutch size was 2.86 ± 0.38 eggs and nest attentiveness was 71.2%. The incubation and nestling periods were, respectively, 13.4 and 17.4 days. Males and females did not differ on nestling provisioning and nest sanitation rates. Nestling provisioning (13.35 ± 6.25 trips/hour) increased with nestling age, while mean brooding time was 37.2% and decreased with nestling age. Apparent nest success was 38.7%, and nest survival according to the Mayfield method was 27.2%. Five nests (20.8%) were parasitised by the Shiny cowbird (Molothrus bonariensis), and we recorded five events of nest-site reuse. We concluded that the most remarkable breeding traits of T. sayaca in comparison with close-related tanagers are the use of anthropogenic nest sites, the higher clutch size and number of feeding trips, and the longer nestling period.     

Reproductive biology of the endangered wattled curassow (Crax globulosa; Galliformes: Cracidae) in the Juruá River Basin,Western Brazilian Amazonia

The reproductive biology of Crax globulosa is virtually unknown, this knowledge comprised of only a few anecdotal notes. We found nine nests of Crax globulosa in the middle section of the Juruá River, western Brazilian Amazon, during the dry season. Nests averaged 22.5 m from water and 13.3 m above the ground. We observed two nest types: five made of twigs, leaves and vines, and four within a bromeliad. All nests contained two eggs, but six (67%) were subsequently predated. A female tagged with a transmitter nested twice during the same breeding season. A chick was monitored together with its parents for > 10 months. In addition to hunting and habitat loss, nest predation could be another threat to this endangered species.     

Nest site characteristics and reproductive success of the Western Tanager ( Piranga ludoviciana ) on the Colorado Front Range

From 1999 through 2001 we located and monitored Western Tanager ( Piranga ludoviciana ) nests in public open-space properties in Boulder County, Colorado. Fifty-four of 58 nests were located in ponderosa pine and the remainder in Douglas-fir. Nests were generally placed near the midpoint of branches in areas of high canopy cover (> 50%) in the middle section of nest trees. Nest height varied as a function of nest tree height, and nests were oriented randomly in relation to trunks of nest trees. Tanager nesting success varied annually, with estimates using the Mayfield method ranging from 11.3% in 2000 to 75.3% in 2001. At least 8 nests were predated, and predation was the primary cause of nest failure. Parasitism by Brown-headed Cowbirds ( Molothrus ater ) occurred in 7 of 17 (41%) nests found during egg-laying or incubation. Clutch size averaged 3.8 in 10 unparasitized nests, but only 2.4 in 8 parasitized nests. Brood parasitism dramatically reduced the number of tanager fledglings produced per nest.     

Reproductive strategies used by moorhens (Gallinula chloropus) colonizing an artificial wetland habitat in south Wales

Over the last ten years, a high-density breeding population (c.180 individuals) of moorhens Gallinula chloropus (Linnaeus) has become established in an artificially created wetland habitat at the Wildfowl and Wetlands Trust (WWT) centre in Llanelli. The reproductive behaviour and success of this population was the subject of an intensive study between 1997–1999. Whilst monogamy was the dominant breeding system used at the site, some individuals bred annually in communal and co-operative groups. The majority of individuals within communal and co-operative groups in 1998 and 1999 were first order relatives. The number of communal groups recorded progressively declined whereas the number of co-operative groups increased over the period of study. Territory size of breeding groups was unrelated to either breeder type or group number. Most nests were constructed in Juncus although many birds also nested in trees and nest boxes intended for captive bred wildfowl. Vegetation height above nests strongly influenced breeding success, and nest site choice at the site was partially determined by vegetation management practices. Such practices may have been responsible for decreased nesting success in specific areas. Rats were the principal egg predators on site accounting for approximately 80% of eggs predated. The study reveals how the reproductive dynamics of this opportunistic bird influences its successful colonization of a new habitat.     

Natural history of the Lined Seedeater Sporophila lineola (Aves: Thraupidae) in southeastern Brazil

The Lined Seedeater (Sporophila lineola) is a migratory species that inhabits a variety of open habitats in South America. We studied the breeding biology and territorial behaviour of a colour-banded population of the species in the Universidade Federal de Viçosa, Campus Florestal (1–19,8808ºS, –44,4136ºW), during two breeding seasons (2014/2015 and 2015/2016), which spans from December to April. We monitored 74 nests of this species. The nest is a low cup supported between a fork. Nests are mainly built with grass stems and rootlets, with spider-web used to hold the material together and to bind the nest to its supporting plant. Females are solely responsible for nest building and incubation, which is synchronic, and also for feeding nestlings to a large extent. Males are responsible for defending the territory, which corresponds to a small portion of the home range restricted to the nest environs, and also feed the nestlings. Mean clutch size is two eggs (78% of nests monitored), with clutches of three (20.3%) and four (1.7%) eggs also observed. Eggs are whitish, covered with dark brown blotches and spots to a variable extent. Mean incubation period, considered as the period between the onset of incubation and hatching of the first egg, is 11 days. Nestling period, considered as the period between hatching of the first egg and fledging of the last young, is 10 days. During the first breeding season, the simple percentage of successful nests was 34.1%, while the Mayfield success was 29.8%, with slightly higher values observed during the second breeding season, with 39.4% and 35.7%, respectively. We recorded, for the first time, three cases of polygamy in the species. We also recorded breeding site fidelity for the first time in the species, with males returning to the same territory owned in a previous breeding season.     

Architecture,composition and placement of nests of the Cipo Canastero Asthenes luizae (Aves: Furnariidae), a bird endemic to Brazilian mountaintops

Cipo Canastero (Asthenes luizae) is a bird endemic to Brazilian mountaintops, inhabiting rock outcrop habitats of the campos rupestres in the southern Espinhaço Range. Available data about Cipo Canastero’s breeding biology are scarce, incomplete or inconsistent. All nests found to date were built in the plant Vellozia nivea. Based on 84 nests found from 2009 to 2017 in four sites at Serra do Cipó, we described in detail their nesting habits focusing on three groups of characters: nest architecture, composition, and placement. Also, we described nest building. Our major new findings on the nesting habits of A. luizae were: three nest layers distinguishable, inner lining covering the entire nest interior, tunnels and tubes are absent, and the nest sites are not restricted to V. nivea. We recorded a wide range of nest sites, from ground, grasses and rupicolous bromeliads to shrubs and trees, including at least 30 supporting-plant species. Nest supports varied among study sites. Nest building lasted 22 days (one nest) and was done by both members of the pair. Our data can be useful for species conservation and contribute to the knowledge of the natural history of the genus Asthenes.     

Limitations on Canada Goose production at Fish Springs National Wildlife Refuge

At Fish Springs National Wildlife Refuge, only 18 to 34 Canada Goose goslings were fledged per year from 1989 to 1993. In addition to the number of breeding pairs, a wide variety of variables can influence goose production, including clutch size, and nest, egg, and fledging success. We examined these variables at Fish Springs in 1996 and 1997 by finding and monitoring nests, and then following broods. We found that despite a limited number of breeding pairs on the refuge, production was further limited by poor ground nest success and low fledging success. Only 51.2% ( n = 22) of ground nests produced hatchlings vs. 86.4% ( n = 19) of platform nests. Of all eggs that hatched, 36.8% ( n = 57) fledged successfully. Predation and human disturbance are discussed as major factors contributing to mortality.     

Breeding biology of the threatened Campo Miner Geositta poeciloptera (Aves: Scleruridae), a Neotropical grassland specialist

The Campo Miner is a threatened grassland passerine endemic to the South American Cerrado, whose life history is almost unknown. In this paper, we studied during three breeding seasons (2014 to 2016) the breeding biology of a colour banded population of the species found in the Upper Rio Grande Grasslands, south-eastern Brazil. We found 98 nests, 81 of which became active and were monitored. The Campo Miner breeds in frequently burnt-and-grazed natural grasslands, successfully nesting in highly disturbed sites, such as dirt banks along roads and even in mine pits. The species is socially monogamous and both parents build the nest, which is a cavity/with-tunnel/simple/platform type. The nest chamber is lined with a platform made of grass fragments, charcoal, hairs, and mammal faeces. The most common clutch size is three eggs (n = 66), with some nests containing one (n = 1), two (n = 12) or four eggs (n = 2). The egg is white and pyriform and the incubation, performed by both parents, lasts 17.5 days. Mean nestling period is 15.5 days, with both parents feeding the young. Breeding season lasted for about 125 days (August to December) and multiple breeding attempts in a single season were common, with a maximum of three attempts recorded. All species of Scleruridae built their nests inside cavities dug in the soil with an access tunnel to it, where they lay a small clutch (usually 2–3 white eggs), but no other species in the family has been studied in detail to date. Further studies are required to understand why a species apparently tolerant to anthropogenic impacts such as G. poeciloptera can be so rare, patchily distributed and threatened throughout its range.     

Nesting and brood-rearing characteristics of Chukars in west central Idaho

We analyzed attributes from 23 nests (10 renests) and 46 brood locations of radio-marked Chukars ( Alectoris chukar ) in the lower Salmon River canyon of west central Idaho in 1995 and 1996. Nesting effort was 100%, apparent nest success was 45%, and estimated time from destruction or abandonment of a nest to initiation of laying a subsequent nest averaged 13 ± 5 days s x . Average clutch size for 1st nests (14.5 ± 1.0) was greater ( P = 0.017) than renests (10.4 ± 1.1). Cover types used by nesting Chukars included grass/forb (48% of nests), rock (43%), and shrub (9%), whereas the most common structure used for nests was rock outcrop (57%). Chukars did not use yellow starthistle ( Centaurea solstitialis ) habitats differently from what was expected ( P = 0.08) for nesting, but birds with broods selected areas with less starthistle ( P < 0.001). Chukar broods, which averaged 12.0 ± 1.1 chicks, used shrub and grass/forb cover types approximately equally (43% and 47% of locations, respectively) but rock habitats infrequently (11%).     

Productivity, food habits, and associated variables of Barn Owls utilizing nest boxes in north central Utah

Productivity and food habits of the Barn Owl ( Tyto alba ) utilizing nest boxes in Juab, Utah, and Salt Lake counties, Utah, During 1979-1984 were examined. Average clutch size was 5.8 eggs for the 6-yr period; mean number fledged was 3.9 young per successful nest. While severe weather during the 1981-82 winter did not result in significant decrease in productivity during the 1982 breeding season, it may have resulted in a significant overproduction of female young. Barn Owls in north central Utah fed almost exclusively on mammalian species, particularly Microtus spp. Difference in clutch size between areas and years may be a response to availability as well as abundance of prey.     

Reproductive ecology of Dusky Flycatchers in montane meadows of the central Sierra Nevada

Avian species with expansive ranges or those that occupy more than one vegetative association may vary in aspects of their life histories across their ranges. The distribution of Dusky Flycatchers encompasses a variety of vegetative associations, including riparian communities. However, much of the literature on this species details studies conducted in upland areas. Our objectives were to describe the breeding ecology and fecundity of Dusky Flycatchers nesting in montane meadows of the central Sierra Nevada, California. We monitored 36 territories and located 37 Dusky Flycatcher nests in 8 meadows. Average clutch size was 3.9 eggs. Egg laying, incubation, and nestling stages were 4, 15.4, and 16.4 days, respectively. Eighteen nests successfully fledged young, with an average of 3.3 fledglings per successful nest. Nest success was 43% and nest predation was the leading cause of nest failure. Estimated annual fecundity was 1.62 fledglings per pair; however, because all renesting attempts were not located, this should be viewed as the minimum annual fecundity. Dusky Flycatchers we monitored may have had higher fecundity than those nesting in upland areas because riparian areas often have higher arthropod abundances. While the importance of riparian conservation to riparian-obligate bird species is obvious, our study indicates that these areas also may be of value to Dusky Flycatchers that breed in riparian areas and upland areas.     

Yellow pine chipmunks cannot climb quaking aspens: implications for avian nest site selection

Predation of eggs or nestlings is generally believed to be the most influential factor limiting passerine reproductive success. Thus, there should be strong selective pressures for birds to place their nests in sites that are inaccessible to predators or that are less likely to be discovered by them. We found and monitored 231 nests of 4 species of arboreal, cup-nesting birds: Western Wood-Pewee ( Contopus sordidulus ), Warbling Vireo ( Vireo gilvus ), American Robin ( Turdus migratorius ), and Yellow-rumped Warbler ( Dendroica coronata ). We determined strength of nest tree species selection by comparing nest trees and tree species availability. Western Wood-Pewees and Warbling Vireos demonstrated strong preference for placing nests in quaking aspen ( Populus tremuloides ). Yellow-rumped Warblers showed a weak preference for aspen, and American Robins demonstrated no preference. We designed a series of experiments to determine whether yellow pine chipmunks ( Tamias amoenus ), an abundant nest predator, could climb aspen trees and, if so, what factors might prevent them from doing so. Yellow pine chipmunks were unable to climb aspen but showed no difficulty in climbing and maneuvering on lodgepole pine ( Pinus contorta ) boles, which were identical in diameter to aspen boles. Refuge from chipmunks as potential nest predators is likely contributing to nest site selection for a few arboreal cup-nesting bird species where aspen trees are available.     

Brood parasitism and nest survival of Brown-headed Cowbird hosts at high-elevation riparian sites in the eastern Sierra Nevada, California

Deciduous riparian ecosystems in the western United States provide habitat for a higher density of breeding birds than reported for any other avian habitat type and provide habitat for more breeding bird species than adjacent uplands. On the east slope of the Sierra Nevada, riparian ecosystems make up Molothrus ater )&mdash;an obligate brood parasite that forages on bare ground and feedlots but typically commutes to distinct shrubland or woodland habitats for breeding. We examined nest survival, brood parasitism, breeding phenology, and causes of nest failure for birds at North Lake and Rock Creek: 2 high-elevation (>2500 m) riparian breeding habitats adjacent to recreational development and within cowbird commuting distance to additional potential foraging sites. Nest survival tended to be higher for host species at Rock Creek than for those at North Lake, but parasitism rates were not significantly different between plots. Of 21 open-cup nesting species, 12 were parasitized. We found the highest rate of parasitism (92%) for Warbling Vireos ( Vireo gilvus ) at North Lake, and parasitism contributed to lower total nest survival there (14%). For nearly all species, parasitized nests were less successful and produced fewer young than nonparasitized nests. However, predation was the leading cause of complete nest failure across all species and contributed to the lowest total nest survival estimates for Western Wood-Pewees ( Contopus sordidulus, 11%) and Dusky Flycatchers ( Empidonax oberholseri, 15%) at North Lake and for Dark-eyed Juncos ( Junco hyemalis, 15%) at Rock Creek. Nest survival was relatively high for Western Wood-Pewees (41%) at Rock Creek and for Yellow Warblers ( Dendroica petechia, 47%) at North Lake. We noted whether the arrival of pack animals at pack-station corrals contributed to variation in cowbird numbers at corrals or in parasitism rates at the 2 sites. Cowbirds occupied corrals before and after pack-stock arrival, and most host clutches were completed prior to pack-stock arrival at nearby corrals, suggesting that the presence of pack animals did not directly affect cowbird host species.     

Breeding biology of the rapids frog Limnomedusa macroglossa (Anura: Cycloramphidae) in southern Brazil

Limnomedusa is a monotypic genus that occurs in association with rocky outcrops and stream beds. Based on observational and mark–recapture fieldwork from 2005 to 2008, we report the breeding biology of Limnomedusa macroglossa in southern Brazil. The reproductive season lasted from late August to early February. Tadpoles were recorded from early September to late February. A clear pattern of emergence/recruitment was observed in juveniles. The occurrence of reproductive activities was clearly related to the longest photoperiods, when the highest temperatures occur. Males called from rocky or concrete substrates, mostly under rocks. Amplexus was axillary and the operational sex ratio was nearly even. Spawn occurred in lentic water bodies but tadpoles also completed their development in slow‐flowing water. Although using similar habitats for reproduction, L. macroglossa reached lower levels of specialization toward terrestriality than did the cycloramphids Cycloramphus and Thoropa. We classify L. macroglossa as a breeding habitat specialist that would be threatened by river damming.     

Reproductive ecology of a Tibetan frog Nanorana parkeri (Anura: Ranidae)

Endemic to the Tibetan Plateau, Nanorana parkeri figures among the highest altitude amphibians in the world. The present work, which was conducted in an alpine marsh at 4300 m altitude, is the first report of the species’ reproductive ecology. The breeding season, as indicated by the presence of amplectant pairs and fresh eggs in ponds, lasted from early Mary to early July. The ratios of adult male to female were 1.3 in hibernation ponds and 2.3 in spawning ones. Males were smaller than females. Amplexus was typically axillary (81.7%), with a few exceptional amplexus in which a male clasped another male or object rather than gravid females. Scramble competition occurred in 6.8% of the normal amplexus located. The body sizes of amplexed couples correlated positively. Deposited eggs were attached to submerged plants solitarily (60.5%) or in small clusters (39.5%), and the scattered arrangement of individual eggs could be a strategy to ensure embryonic development in oxygen-poor environments. Clutch size averaged 189 [standard deviation (SD) = 64], and correlated positively with female body size; egg size averaged 2.18 mm (SD = 0.10), independent of female body size; both traits within a clutch were negatively related with each other even controlling for female body size. Relatively few and large eggs laid by the Tibetan frogs, compared with those by lowland aquatic-spawning anuran species, should be adaptive to the harsh high-altitude conditions. Larvae hatched from eggs after 16.4 days on average (SD = 5.8). Froglets emerged between late July and early August, but some tadpoles were present in winter. These findings may help to understand the evolution of amphibians in extreme environments and to protect these remote species.