Registered users receive a variety of benefits including the ability to customize email alerts, create favorite journals list, and save searches.
Please note that a BioOne web account does not automatically grant access to full-text content. An institutional or society member subscription is required to view non-Open Access content.
Contact firstname.lastname@example.org with any questions.
From 1971 through 2003, Ovenbirds (Seiurus aurocapilla) at the Hemlock Hill Biological Research Area in northwestern Pennsylvania never bred in forest interior. Instead, they exhibited atypical habitat selection for breeding by occupying regenerating forest edges. Pairs in 14 territories, the entire population, showed normal annual return rates and pairing rates compared with other studies. For this ground-foraging bird, other studies showed that deep soil litter is preferred—but at my study site, soil litter depth in Ovenbird-occupied areas was lower than that found in the unoccupied forest interior. During May, July, and August, songs played in forest interior to attract Ovenbirds to settle there were unsuccessful. I tested the hypothesis that eastern chipmunk (Tamias striatus) abundance influenced this atypical habitat selection. Chipmunks were nearly absent from Ovenbird territories, but were abundant in the forest interior. I discuss habitat selection in birds in relation to simple cues and relate this to variation in habitat selection and use found in Ovenbirds.
In the temperate zone, few plants produce fruit during the peak of the avian breeding season when arthropods are abundant. This study examined avian frugivory on red elderberry (Sambucus racemosa pubens), a gap-specialist that fruits in late June and early July. First, we videotaped fruiting elderberry plants (n = 67 hr) within a forest to determine which avian species ate elderberry fruit. The birds that fed most frequently on red elderberry fruits were Scarlet Tanagers (Piranga olivacea) and Rose-breasted Grosbeaks (Pheucticus ludovicianus). We then analyzed radiotelemetry data for Scarlet Tanagers to determine (1) whether tanagers shifted their territories when elderberry was in fruit, and (2) whether tanagers traveled long distances off territory to visit fruiting elderberry. During the fruiting period, male tanagers shifted their home ranges and spent more time near elderberry bushes; however, they left their territories only 0.25 times per hr and moved an average of only 115 m during trips off territory. These results suggest that while tanagers do focus their activity near fruiting elderberry, they do not leave their territories regularly to find fruit.
In 2001 and 2002, we inventoried the bird communities and vegetation of two 6.25-ha plots in a late-successional spruce-fir (Picea mariana–Abies balsamea) forest of northern Minnesota that was severely disturbed by a 1999 windstorm. We compared these results with those from two nearby plots that were largely unaffected by the storm. Using vegetation data collected from one of the two plots in each location before the disturbance in 1996 and 1998, we examined similarities between plots before and after the storm. The most significant effect of the storm on vegetation was a ≥80% decrease in tree cover and a >100% increase in shrub-layer structure because of trees that were tipped over or snapped off. Of 30 territorial bird species, 9 held territories exclusively in the blowdown, while 2 held territories exclusively in the control. By foraging guild, 10 of 11 (91%) species of ground-brush foragers had more territory cover in the blowdown, while 7 of 13 (54%) species of tree-foliage searchers had more territory cover in the control. Black-and-white Warbler (Mniotilta varia), Chestnut-sided Warbler (Dendroica pensylvanica), Mourning Warbler (Oporornis philadelphia), Yellow-bellied Flycatcher (Empidonax flaviventris), and Red-eyed Vireo (Vireo olivaceus) had significantly (P < 0.05) more territory cover in the blowdown, whereas Blackburnian Warbler (Dendroica fusca), Golden-crowned Kinglet (Regulus satrapa), and Yellow-rumped Warbler (Dendroica coronata) had more territory cover in the control. Canonical correspondence analysis revealed that differences in avian territory cover were primarily attributable to changes in vegetation structure, in particular the increase of structural debris on the ground and the reduction in tree canopy, occurring because of the wind.
Silviculture in the Ouachita National Forest in Arkansas and Oklahoma has shifted in recent years from mostly even-aged management to a mix of even- and uneven-aged regeneration systems, including group-selection. Researchers have described presence/absence of early-successional bird species in forest openings created by even- and uneven-aged silviculture, but few have examined nest success. We examined occupancy and nest success of three early-successional species—Indigo Bunting (Passerina cyanea), Yellow-breasted Chat (Icteria virens), and Prairie Warbler (Dendroica discolor)—within 6- and 7-year-old openings created by group-selection (uneven-aged, ≤0.8 ha) and seed-tree (even-aged, 11–16 ha) cuts in Arkansas. We found 54 Indigo Bunting nests in openings created by seed-tree cuts and 28 in openings created by group-selection cuts (hereafter “seed-tree stands” and “group-selection stands,” respectively). We found 50 Yellow-breasted Chat nests in seed-tree stands, but only 2 were found in group-selection stands. We found 14 Prairie Warbler nests in seed-tree and none in group-selection stands. Mayfield nest success for Indigo Bunting was 30.9% in seed-tree stands and 41.9% in group-selection openings, but there was no difference in daily nest survival (0.952 ± 0.009 and 0.964 ± 0.010, respectively; χ2 = 0.792, P = 0.37). Our data suggest that Indigo Buntings can nest successfully in both regenerating seed-tree and group-selection stands; however, group-selection openings may be too small to support nesting Yellow-breasted Chats and Prairie Warblers. Public concerns about clear-cutting have resulted in increased use of uneven-aged management by the USDA Forest Service. However, before widespread implementation of group-selection cutting, additional research should be conducted to evaluate the effects of this management strategy on Neotropical migratory bird communities.
Speed (km/hr) during flight is one of several factors determining the rate of migration (km/ day) and flight range of birds. We attached 26-g, back-mounted satellite-received radio tags (platform transmitting terminals; PTTs) to adult female Northern Pintails (Anas acuta) during (1) midwinter 2000–2003 in the northern Central Valley of California, (2) fall and winter 2002–2003 in the Playa Lakes Region and Gulf Coast of Texas, and (3) early fall 2002–2003 in south-central New Mexico. We tracked tagged birds after release and, in several instances, obtained multiple locations during single migratory flights (flight paths). We used data from 17 PTT-tagged hens along 21 migratory flight paths to estimate groundspeeds during spring (n = 19 flights) and fall (n = 2 flights). Pintails migrated at an average groundspeed of 77 ± 4 (SE) km/hr (range for individual flight paths = 40–122 km/hr), which was within the range of estimates reported in the literature for migratory and local flights of waterfowl (42–116 km/hr); further, groundspeed averaged 53 ± 6 km/hr in headwinds and 82 ± 4 km/hr in tailwinds. At a typical, but hypothetical, flight altitude of 1,460 m (850 millibars standard pressure), 17 of the 21 flight paths occurred in tailwinds with an average airspeed of 55 ± 4 km/hr, and 4 occurred in headwinds with an average airspeed of 71 ± 4 km/hr. These adjustments in airspeed and groundspeed in response to wind suggest that pintails migrated at airspeeds that on average maximized range and conserved energy, and fell within the range of expectations based on aerodynamic and energetic theory.
Sympatric avian brood parasites may compete for the same nests to parasitize. Host-resource partitioning, or “alloxenia,” is exhibited by several Old World cuckoos where they are sympatric in Africa, Japan, and Australia. I examined host use by sympatric Brown-headed Cowbirds (Molothrus ater) and Bronzed Cowbirds (M. aeneus) from 1997 to 1999 in pine-oak and montane riparian forests in southeastern Arizona. Bronzed and Brown-headed cowbirds partitioned hosts by host body size. Brown-headed Cowbirds did not parasitize larger hosts (i.e., Western Tanager, Piranga ludoviciana; and Hepatic Tanager, P. flava), while Bronzed Cowbirds did not parasitize smaller hosts (i.e., Painted Redstarts, Myioborus pictus; and Bell's Vireos, Vireo bellii). Although there was some host overlap (only 2/7 parasitized host species were parasitized by both cowbird species), only 3/48 nests (all Plumbeous Vireo, V. plumbeus) contained eggs of both parasite species. Parasitism by sympatric cowbirds in southeastern Arizona appears to fit the pattern of alloxenia.
Since 2000, we have been banding American Oystercatcher (Haematopus palliatus) chicks at Cape Lookout and Cape Hatteras national seashores as part of a long-term demographic study. Between 2000 and 2002, we banded 23 chicks. We report on resightings of eight chicks that returned to the Outer Banks of North Carolina in the summers of 2003 and 2004. These are the first records of American Oystercatcher chicks resighted near their natal areas in their 2nd and 3rd years. The 3-year-old birds appeared to be paired and acted territorial, whereas the 2nd-year birds were observed alone or in groups and did not exhibit territorial behavior. Our observations suggest that the American Oystercatcher's life history is similar to that of the Eurasian Oystercatcher (Haematopus ostralegus).
In 1999, we compared foraging success rates (captures/min) and foraging behaviors of Wood Storks (Mycteria americana) at tidal (Georgia) and non-tidal freshwater (South Carolina) foraging sites. Foraging success rates were 30 times greater at the tidal site, but storks foraging in tidal areas only fed at low tide, which limited their foraging time at that site. On-site behaviors indicated the window of prey availability. Storks at the tidal site engaged almost exclusively in foraging behaviors, whereas storks at the non-tidal site devoted more time to other, non-foraging behaviors (e.g., preening, resting). The greater foraging success rate associated with the tidal site suggests that salt marsh/tidal creek habitats are high-quality foraging areas.
Sexual dimorphism in color and pattern of contour feathers is rare in juvenile songbirds. We describe how captive-bred juvenile males of Scottish Crossbill (Loxia scotica) and nominate Red Crossbill (L. curvirostra curvirostra) can be differentiated from females prior to prebasic molt by an unstreaked patch on the males' upper breast. There may be a functional relationship between sexual dimorphism and the formation of pair bonds or breeding while the birds are still in juvenile plumage. Sexually dimorphic Red Crossbills and Bearded Tits (Panurus biarmicus) are known to form pair bonds, and even breed successfully, while still in juvenile plumage.
I present a description of the nest, eggs, and nestlings of the Pale-eyed Thrush (Platycichla leucops). In addition, I present data on nest temperatures and incubation patterns. Two cup-shaped nests were found at a cloud forest site in the Central Andes of Colombia, both made of moss and containing two greenish-colored eggs with brown blotches. Generally, the incubating female spent the night on the nest. She left the nest at dawn, returned several times during the day and at dusk. Only the female incubated, but the male helped feed the nestlings. Nest temperature varied during incubation between 24° and 27° C, which was several degrees above ambient temperature. There were differences between the two nests in the rate of cooling after the female left the nest at dawn, probably related to nest placement. Nest microclimate was affected by microhabitat and adult incubation behavior.
We report an observation of interspecific nest sharing between Red-breasted Nuthatches (Sitta canadensis) and Mountain Chickadees (Poecile gambeli) near Williams Lake, British Columbia, Canada. The nest contained two Red-breasted Nuthatch and three Mountain Chickadee nestlings. The nest was attended by a pair of Mountain Chickadees earlier in the observation period and later by an adult female Red-breasted Nuthatch; all five nestlings fledged. Competition for nest sites due to a decrease in cavity availability may have contributed to this occurrence.
On 22 July 2004, we found a Nelson's Sharp-tailed Sparrow (Ammodramus nelsoni) nest in Sheridan County, Montana, containing a single Brown-headed Cowbird (Molothrus ater) nestling that was about to fledge. A punctured sharp-tailed sparrow egg was found below the nest. This is the second definitive report of cowbird brood parasitism of a Nelson's Sharp-tailed Sparrow nest and the first indicating successful rearing of a cowbird by this host species. The impact of cowbird parasitism on nesting success of Nelson's Sharp-tailed Sparrow has not been studied, but our record indicates that nest failure (i.e., producing no host young) may be an outcome for some nests of this species.
Dunking behavior, the immersion of food items in water, is a relatively rare behavior in birds. I observed American Crows (Corvus brachyrhynchos) dunking several types of food in rain puddles at Mont-Royal Park, Montréal, Québec, Canada. Pieces of dry bread and unshelled peanuts were provided in two experiments to test the potential effects of item size (bread) and shell softening (peanuts) on crow behavior. Crows dunked large pieces of bread more often than small ones. Dunking unshelled peanuts did not speed up the opening process. These observations further support the suggestion that food dunking among birds facilitates food ingestion by softening large, hard items.
Cooperative hunting is a behavior rarely observed in passerine birds. I observed two immature Northern Shrikes (Lanius excubitor invictus) apparently hunting cooperatively while preying on American Tree Sparrows (Spizella arborea) in central Alaska. During each of three foraging attempts, both shrikes appeared to work together to flush prey from dense cover into the open where it was then pursued. Cooperative hunting in this otherwise solitary species may be an adaptive behavior among inexperienced birds to increase their foraging efficiency, or to compensate for seasonal fluctuations in the accessibility or availability of prey.
We describe a photodocumented field observation in Sinaloa, Mexico, of a head-down (or “preening invitation”) display performed by a male Bronzed Cowbird (Molothrus aeneus), which elicited both grooming and pecking responses from a female Great-tailed Grackle (Quiscalus mexicanus). Previously, such displays by parasitic cowbirds and responses by conspecific or various heterospecific bird species have been documented mainly under aviary conditions; most field observations have involved Brown-headed (M. ater) and Shiny (M. bonariensis) cowbirds. The function and evolutionary significance of such interspecific interactions remain elusive, but continued documentation of such occurrences may help elucidate their biological significance.
We report on a female House Finch (Carpodacus mexicanus) eating one of her own eggs from a clutch of six on the 3rd day of incubation. This observation is a confirmed case of filial cannibalism in the egg stage. The reason for this behavior is unknown, but we suggest and discuss three possibilities: (1) an idiosyncratic response to human disturbance, (2) removal of a damaged egg from the nest, and (3) facultative brood reduction in the egg stage.
I observed a pair of Orange-breasted Falcons (Falco deiroleucus) in Tikal, Guatemala, on 30 December 2003 and 1 January 2004. I observed the birds flying through wet foliage as a means of bathing, which has not been described previously for this species. During a morning with light rain, an adult falcon took off from a perch, flew low over the forest canopy, and appeared to crash intentionally into the wet, upper foliage of emergent trees before returning to its perch. I observed three repetitions of this behavior.
I observed a juvenile male Bare-necked Umbrellabird (Cephalopterus glabricollis) forage on arthropods flushed by a large swarm of the army ant Eciton burchellii in the Caribbean foothills of Costa Rica. Apparently, this is the first report of this species attending an army ant swarm. At least 60 birds of eight different species were foraging at that swarm, the largest assemblage of army ant-following birds reported in the Neotropics.