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.     

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 )—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.     

Nesting ecology of Yellow Warblers ( Dendroica petechia ) in montane chaparral habitat in the northern Sierra Nevada

The Yellow Warbler ( Dendroica petechia ) is considered a riparian specialist in much of western North America, but in California it also breeds in a second habitat type: montane chaparral of the Sierra Nevada and southern Cascades. We monitored Yellow Warbler nests in montane chaparral and assessed their poorly known nesting ecology in this habitat. We also conducted point counts in upland habitat throughout the region. We determined habitat associations for Yellow Warblers based on nest site and point-count vegetation data; nests were predominantly in bush chinquapin ( Chrysolepis sempervirens ) and greenleaf manzanita ( Arctostaphylos patula ), and point-count abundance was most strongly associated with high overall shrub cover. The importance of montane chaparral for a number of shrub-dependent Sierran birds is well documented, yet the chaparral is threatened by various practices including fire suppression, closed-canopy-focused forest management, and understory fuels-reduction treatments. Although Yellow Warblers are far more abundant in wet mountain meadow riparian habitat in the region, we recommend that management of montane chaparral habitat consider this species and the requirements of other shrub-nesting birds.     

Western Scrub-Jay breeding biology in central Colorado

The breeding ecology of the Western Scrub-Jay ( Aphelocoma californica ) in the midwestern United States is relatively unknown compared with Aphelocoma species in other geographic regions. We examined Western Scrub-Jay breeding biology in Colorado between 1970 and 1992. Incubation was initiated in early April and lasted 16 days, while the nestling stage lasted approximately 17-18 days. Clutch size averaged 4.0 eggs per nest, reproductive success was 25%, and productivity averaged 0.66 fledglings per nest. The low reproductive success and productivity measures may be due to high predator densities in the surrounding suburban landscape. Western Scrub-Jays preferred nesting in eastern red cedar ( Juniperus virginianus ) with nests placed on southern exposures. Western Scrub-Jays bred monogamously and were more similar in their breeding biology to the Island Scrub-Jay ( Aphelocoma insularis ) than to the Florida Scrub-Jay ( Aphelocoma coerulescens ).     

History and status of the Franklin's Gull on Malheur National Wildlife Refuge, Oregon

Franklin's Gulls first arrived in southeast Oregon in 1943, but the first nest was not located until 1948. From 1949 to 1964 gull numbers showed annual fluctuations. An increase began in 1965 and continued through 1980. By 1980 an estimated 2500 Franklin's Gulls were nesting on Malheur National Wildlife Refuge, Harney County, Oregon. The species arrives in April and nesting begins by 1 June. Average nest and egg measurements were similar to those from other areas within the species range.     

Breeding behavior of the Plumbeous Vireo in New Mexico

The Plumbeous Vireo ( Vireo plumbeus ) is a poorly studied songbird species that breeds within the interior western United States and Mexico. We studied the breeding behavior of Plumbeous Vireos within pinyon-juniper habitats in northeastern New Mexico in 1996 and 1997. Over both years we located and monitored 40 nests and conducted behavioral observations throughout the nesting cycle. From these observations we described and compared basic behavioral traits of male and female vireos during their nest-building, egg-laying, incubation, and nestling stages, and their response to potential predators near the nest. Male vireos displayed potential nest sites to females, but the females selected the site to be used and built most of the nest. Vireos often did not initiate egg-laying until 2-3 d after nest completion. The female tended to incubate eggs and brood nestlings more than the male, but both parents contributed equally in provisioning the young. Brown-headed Cowbirds ( Molothrus ater ) parasitized 77% of nests in 1996, 63% in 1997, and parasitism was the primary cause of nest failure in this population. The conspicuousness of vireos around the nest, particularly during the nest-building stage, may contribute to high parasitism levels. Vireo aggression near the nest may also act as a cue to help cowbirds locate nests.     

Nesting phenology and productivity of birds in the White and Inyo Mountains, California, as assessed with nest-boxes

Nest-boxes were monitored from 1988 to 1992 on 5 grids in the pinyon-juniper ( Pinus-Juniperus ) woodlands of the White and Inyo Mountains, California, to determine breeding phenology and productivity of cavity-nesting birds, and characteristics of used and non-used nest-boxes. We found a total of 112 nests of 6 species. Bewicks Wrens ( Thryomanes bewicki i; 64 nests), Mountain Chickadees ( Poecile gambeli ; 18), Ash-throated Flycatchers ( Myiarchus cinerascens ; 12), and Juniper Titmice ( Baeolophus ridgwayi ; 11) were the most common species utilizing the boxes. Nest phenology and numbers of young were similar to values reported elsewhere in the literature for the species, although nesting success for Mountain Chickadees appeared lower in our study. Chickadees were associated with relatively dense, mature vegetation on southern slopes. Juniper Titmice used areas with tall juniper shrubs and generally sparse vegetation. Bewicks Wrens used areas with short trees, sparse vegetation, and many stumps. Nest-boxes were underutilized (< 15% use) by most species relative to their availability and relative to detected abundances of the species. We suggest that nest-boxes can provide valuable breeding biology information and can potentially increase the productivity of rare and cavity-limited species.     

Nesting ecology of waterbirds at Grays Lake, Idaho

Montane wetlands provide valuable habitat for nesting waterfowl and other waterbirds in the western United States, but relatively little information is available about the nesting ecology of their waterbird communities. We describe the general nesting ecology of breeding waterbirds at a large, shallow, montane wetland in southeastern Idaho during 1997-2000. Habitats include upland grasslands and intermittently to semipermanently flooded wetland habitats. We located a total of 1207 nests of 23 bird species: Eared Grebe ( Podiceps nigricollis ), Canada Goose ( Branta canadensis ), Mallard ( Anas platyrhynchos ), Gadwall ( A. strepera ), American Wigeon ( A. americana ), Green-winged Teal ( A. crecca ), Blue-winged Teal ( A. discors ), Cinnamon Teal ( A. cyanoptera ), Northern Shoveler ( A. clypeata ), Northern Pintail ( A. acuta ), Redhead ( Aythya americana ), Canvasback ( A. valisineria ), Lesser Scaup ( A. affinis ), Ruddy Duck ( Oxyura jamaicensis ), Northern Harrier ( Circus cyaneus ), American Coot ( Fulica americana ), Virginia Rail ( Rallus limicola ), Greater Sandhill Crane ( Grus canadensis tabida ), American Avocet ( Recurvirostra americana ), Long-billed Curlew ( Numenius americanus ), Wilson's Snipe ( Gallinago delicata ), Wilson's Phalarope ( Phalaropus tricolor ), and Short-eared Owl ( Asio flammeus ). Most nests were initiated in May-early June and were terminated (hatched or destroyed) by the 3rd week of June. Mean daily survival rate (DSR) for Canada Goose nests was 0.954 ± 0.005 ( s ￣x ; n = 127 nests), equivalent to Mayfield nest success of 21%. Mean DSR for dabbling duck nests over all 4 years was 0.938 ± 0.006 ( n = 41), equivalent to Mayfield nest success of 11%. For all other species where we found > 10 nests each year (Eared Grebe, Redhead, Canvasback, Coot, Sandhill Crane, American Avocet, and Wilson's Snipe), > 50% of nests found hatched at least 1 young. Success rates for geese, cranes, and ducks were lower than reported for Grays Lake during 1949-1951 and lower than most other wetlands in the region.     

Behavioral activities and breeding success of Willow Flycatchers in the Sierra Nevada

Observing survival and how individuals allocate time can provide insight into a species' ability to tolerate environmental constraints. We studied the Willow Flycatcher ( Empidonax trallii ) in the Sierra Nevada to determine if there were behavioral differences between pairs that successfully produced offspring and those that did not. This information will advance understanding of why these birds are declining in the Sierra Nevada and contribute to recommendations that may help to conserve them. We studied birds in 13 meadows in 2000 and 2001 using continuous focal-animal observations. Of the 43 territories we observed, 11 were occupied by males who never paired with a female, leaving 32 pairs for analysis. Of the 32 pairs, 13 were successful at breeding on their 1st attempt, and 9 pairs failed at their initial try but were successful on their 2nd breeding attempt. Throughout the breeding season, Willow Flycatchers spent 77%-78% of the day loafing during territory establishment and nest building, and loafing reached a low of 49% of the time budget during the nestling stage. Unsuccessful pairs spent on average 34% more time perching than their successful counterparts, while successful pairs spent on average 48% more of their time on the nest than unsuccessful pairs. Willow Flycatchers doubled the time spent foraging during the nestling phase because they had to meet the daily intake requirements for their young and themselves. Our results suggest that birds that spent more time on the nest and less time vocalizing had a significantly higher probability of successfully producing young because they were able to protect nests from predators, nest parasites, and inclement weather.     

Breeding biology of Mountain Plovers ( Charadrius montanus ) in the Uinta Basin

The known Mountain Plover population breeding on the Myton Bench, Duchesne County, Utah, is small, composed roughly of 30 adults and young after each breeding season. Currently, its location is peripheral to the species main range. This shrub-steppe breeding habitat differs from the shortgrass prairie habitat with which this bird is historically associated. Between 1996 and 1998 we made observations at nesting sites located consistently in 2 concentrated areas surrounded by large tracts of similar habitat. Activity may be focused in these specific areas because of breeding-site fidelity; this behavior is common among most shorebirds and has been documented for the Mountain Plover in Colorado. Also, Mountain Plovers are social and tend to choose nest sites near others. Most nests in Utah were located within close proximity of mounds of white-tailed prairie dogs ( Cynomys leucurus ), and all were situated near roadways or oil well pads. Mountain Plovers were often observed with broods on these bare areas at night. We conclude that Mountain Plovers on the Myton Bench are distributed in clumped breeding colonies within large areas of apparently favorable habitat.     

The evolution of nest building and communal nesting in Ageniellini (Insecta: Hymenoptera: Pompilidae)

Pompilid wasps prey upon spiders and use a single spider per nest cell. The majority of species dig simple burrows in the soil in which to cache their spider, on which an egg is laid. The nest is not revisited, but another nest is prepared elsewhere. However, members of the tribe Ageniellini show much diversity in nesting behaviour. Species of the genus Ageniella nest in pre-existing cavities in the soil, closing off their cells with bits of debris. Most other Ageniellini that have been studied carry water to make mud pellets, from which ovoid nest cells are made. Usually a series of such cells is made in close proximity, often under loose bark or stones or in hollow stems. A few species make free nests above ground, usually in protected places or with thick mud walls. In some cases nest sites are known to be re-occupied by members of successive generations. Several species are known to nest communally, co-operating in nest defense and in cell building. In many ways the evolution of nesting behaviour in this group parallels that in the mud-using Vespidae, but the use of a single prey per cell precludes development of progressive provisioning and of eusociality similar to that of many Vespidae.     

Nesting dynamic and sex allocation of the oil-collecting bee Centris (Heterocentris) analis (Fabricius, 1804) (Apidae: Centridini)

The study of nesting biology is an important biological aspect for both conservation and management, but despite this, only a few of the over 20,000 described bee species have had their nesting biology studied. The aim of this study was to describe and analyse the nesting biology and dynamic of an aggregation of the cavity-nesting bee species Centris analis during one generation. Twenty-eight females were marked and had their nesting activities documented, 64 nests were sampled, and 113 individuals emerged from these nests. An asymmetry in the sex allocation was observed for this species, and the sex ratio was male-biased in the first nests built. Nonetheless, considering an individual-level perspective, the females showed different strategies, with some of them producing more daughters, other females producing more sons, and still others producing an equal proportion. The productivity per female was low compared to that of other solitary bee species, and the females displayed an aggressive usurpation behaviour against conspecific females and performed an intraspecific parasitism. As the substrate used to nest is a limiting factor for this species, the usurpation behaviour may be an important strategy that could increase the chance of nesting. A few males used the nesting site as a resting place and the fidelity observed to this locale was high. This study provides new information about the natural history of this bee species, which is an important pollinator of both crops and native plant species.     

Nest site selection by Mountain Plovers ( Charadrius montanus ) in a shrub-steppe habitat

The known Mountain Plover population breeding on the Myton Bench, Duchesne County, Utah, is small, composed roughly of 30 adults and young after each breeding season. Currently, its location is peripheral to the species main range. This shrub-steppe breeding habitat differs from the shortgrass prairie habitat with which this bird is historically associated. Between 1996 and 1998 we made observations at nesting sites located consistently in 2 concentrated areas surrounded by large tracts of similar habitat. Activity may be focused in these specific areas because of breeding-site fidelity; this behavior is common among most shorebirds and has been documented for the Mountain Plover in Colorado. Also, Mountain Plovers are social and tend to choose nest sites near others. Most nests in Utah were located within close proximity of mounds of white-tailed prairie dogs ( Cynomys leucurus ), and all were situated near roadways or oil well pads. Mountain Plovers were often observed with broods on these bare areas at night. We conclude that Mountain Plovers on the Myton Bench are distributed in clumped breeding colonies within large areas of apparently favorable habitat.     

Nesting habits of the Japanese foliage spider,Cheiracanthium japonicum (Araneae: Miturgidae): host plant preference based on the physical traits of plant leaves

A Japanese foliage spider, Cheiracanthium japonicum, builds nests with plant leaves. The nests are classified into seven types in relation to the seasons and purposes of nesting. We investigated whether the spider selects a plant species according to the nest type and how the physical traits of leaves influence the spider's plant selection. The difference between the composition of the host plant species used for nesting and that of the seasonal vegetation cover was confirmed. This suggests that the spider chooses the host plant species regardless of its abundance in their habitat. Early juveniles use small living or large dead leaves of various plant species to build moulting nests. Females prefer long and large leaves found in Miscanthus sinensis and Phragmites japonica over other plant leaves to build breeding nests.     

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%).     

On the natural history of the South American pepper frog,Leptodactylus labyrinthicus (Spix, 1824) (Anura: Leptodactylidae)

Some species of Leptodactylus of the L. pentadactylus group lay their eggs outside water but the tadpoles need to reach water to complete the larval phase; other species complete development in terrestrial nests. Here we present details of the reproduction of L. labyrinthicus in south‐eastern Brazil. The proportion of tadpoles and trophic eggs in aged egg clutches was determined, as well as the growth of the tadpoles while in the nest. The gut contents of tadpoles that were in egg clutches of frogs were analysed. Adult males did not differ from females in size and had hypertrophied forearms and an enlarged spine on the thumb. Reproduction was initiated with the first rains of August/September and extended to mid‐January. Calling and spawning occurred at permanent or temporary water bodies. The foam nests were built in excavated basins outside of, but close to the water. The male determined the place of the basin construction; after amplexus, the female completed the excavation. The amplexus was axillary. One female spent the day after spawning in the foam. The eggs were pale grey, the yolk averaging 2.3?mm in diameter. The mean number of eggs was 2101 per egg clutch. The number of tadpoles in individual nests varied between 0.05% and 11.40% in relation to the total laid eggs. The tadpoles entered water when rains flooded the basin. The tadpoles grew to 12 times the weight of an individual egg while in the nest; no nesting tadpole was beyond stage 25. The longest time we followed tadpoles in a nest was 25 days. Tadpoles were found preying upon eggs of three other frog species and upon conspecific eggs. Males fought by grasping each other in a belly‐to‐belly position; the powerful arms and the thumb spines represent weapons. Even though males can reach maturity in the season following birth, small size would prevent them from establishing their own territory. All the species of the L. pentadactylus group may build their foam nests within excavated basins. The basins may protect the eggs and embryos from cannibalistic tadpoles and may have an anti‐desiccation effect. In order to produce trophic eggs, the female may delay laying additional unfertilized eggs until after the male has abandoned the foam nest. Anuran eggs represent an important food item for tadpoles after they leave the nest.     

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.     

Least Bell's Vireo breeding records in the Central Valley following decades of extirpation

The Least Bell&rsquo;s Vireo ( Vireo bellii pusillus ) was listed as state endangered in 1980 and federally endangered in 1986 in response to a sharp population decline and range reduction. This vireo commonly bred in riparian forests throughout the Central Valley of California, but prior to 2005, no nesting pairs had been confirmed in the region in over 50 years. On 29 June 2005, a Least Bell&rsquo;s Vireo nest was located in a 3-year-old riparian restoration site at the San Joaquin River National Wildlife Refuge in Stanislaus County, California. In 2006, a Least Bell&rsquo;s Vireo pair returned to the refuge to successfully breed, followed by an unsuccessful attempt in 2007 by an unpaired female. These records are approximately 350 km from the nearest known breeding population and appear to be part of a growing number of sightings outside of the species&rsquo; current southern California breeding range. These nesting attempts lend credence to the idea that extirpated species can recolonize restored habitat by long-distance dispersal.     

Predation of artificial Sage Grouse nests in treated and untreated sagebrush

We measured predation on 120 artificial Sage Grouse ( Centrarcus urophasianus ) nests in montane sagebrush grassland in northern Utah. We examined nests in areas that had been chained and seeded 25 years previously (treated areas) and in areas that were untreated. Predation rates of artificial nests were higher in areas of untreated sagebrush, even though these areas had greater sagebrush cover, taller shrubs, and greater horizontal plant cover. These results differ from those previously hypothesized for treated sagebrush habitat and may reflect a greater abundance of other potential prey species, especially lagomorphs, in untreated areas that attracted greater densities of predators. In addition, over 80% of nests were depredated by mammals, which hunt using olfaction and are less likely than avian predators to be affected by nest cover. We conclude that, after treated sagebrush has recovered to some degree, predation rates of Sage Grouse nests may be lower in treated sagebrush. Consequently, factors other than nest predation (e.g., winter food, thermal cover, insects, perennial forb abundance) may be more important reasons for preserving mature sagebrush stands for Sage Grouse.