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We describe a new species of gnatcatcher, Polioptila clementsi, from white-sand (varillal) forest at the Allpahuayo-Mishana National Reserve, about 25 km by road west of Iquitos, Peru. To date, the new species is known only from the reserve, and is rare even there. Comparisons of morphological and vocal characters confirm that it is a member of the Polioptila guianensis complex, which comprises at least three poorly known, allopatric taxa ranging from the Guianas and the Rio Negro region through much of Amazonia south of the Amazon River. Roughly equivalent levels of phenotypic differentiation are documented for all taxa east of the Andes, including the new species. In consideration of the fact that some other species complexes in the genus comprise sister taxa showing lower levels of phenotypic differentiation, both morphologically and vocally, we recommend that Polioptila guianensis, P. facilis, and P. paraensis henceforth be recognized as separate species.
RESUMEN.—Describimos una nueva especie de perlita, Polioptila clementsi, del bosque de arena blanca (varillal) de la Reserva Nacional Allpahuayo-Mishana, a 25 km por carretera al oeste de Iquitos, Perú. Hasta la fecha, la nueva especie es conocida solamente de la reserva, y es rara incluso allí. Comparaciones de caracteres morfológicos y vocales confirman que es un miembro del complejo Polioptila guianensis, que comprende al menos tres taxones alopátricos muy poco conocidos, que se extienden desde la región de las Guyanas y el Rio Negro a través de gran parte de la Amazonía al sur del Rio Amazonas. Son documentados niveles aproximadamente equivalentes de diferenciación fenotípica para todos los taxones al este de los Andes, incluyendo la nueva especie. En consideración al hecho de que algunos otros complejos de especies en el género comprenden taxones hermanos que muestran una diferenciación fenotípica menos marcada, tanto morfológica como vocal, recomendamos que de aquí en adelante Polioptila guianensis, P. facilis, y P. paraensis sean reconocidas como especies separadas.
We report movements and home-range sizes of adult Mountain Plovers (Charadrius montanus) with broods on rangeland, agricultural fields, and prairie dog habitats in eastern Colorado. Estimates of home range size (95% fixed kernel) were similar across the three habitats: rangeland (146.1 ha ± 101.5), agricultural fields (131.6 ha ± 74.4), and prairie dog towns (243.3 ha ± 366.3). Our minimum convex polygon estimates of home-range size were comparable to those on rangeland reported by Knopf and Rupert (1996). In addition, movements—defined as the distance between consecutive locations of adults with broods—were equivalent across habitats. However, our findings on prairie dog habitat suggest that home-range size for brood rearing may be related to whether the prairie dog habitat is in a complex of towns or in an isolated town.
We studied the feeding ecology of Long-tailed Ducks (Clangula hyemalis) in two different marine benthic habitats in the Baltic Sea to determine whether there were differences in diet choice, foraging selectivity, body condition, and bird abundance. Our results corroborate earlier suggestions that Long-tailed Ducks exhibit ecological plasticity in selecting winter habitat and food. The majority of Long-tailed Ducks occurred in hard-bottom habitats where they relied on the bivalve Mytilus edulis; however, some of the population wintered in less productive, soft-bottom habitats where they employed a prey-selective foraging strategy, in which they fed on less abundant, but energy rich, crustaceans. Both strategies were apparently viable, as dissected birds in both habitats were in good body condition and had substantial fat reserves.
We summarized published and unpublished information on the reproductive biology and ecology of Jabirus (Jabiru mycteria) in Belize. From 1968 to 1987, 91 individual nests were discovered in 16 of 19 breeding seasons; 69 nests were confirmed as active. Jabiru nests were 15–30 m above ground in Ceiba pentandra (five nests), Pinus caribaea (five nests), Tabebuia ochracea (one nest), Acoelorrhaphe wrightii (one nest), and dead trees (three nests). Most nests (32 of 36) were located in northern and central Belize in isolated, tall, emergent trees (trees with crowns that stand above the surrounding canopy). Nest trees were usually surrounded by riparian forests or seasonally inundated pine-savanna wetlands situated in transitional zones where pine savannah meets coastal lowlands. Two nests were used for at least 10 years. The breeding season began with the transition from wet to dry season (November–December). Earliest eggs were observed on 12 December 1973 and latest eggs on 26 February 1987. Earliest nestlings were observed on 15 January 1970, and young were seen on nests as late as 28 May 1973. Young birds fledged 100 to 115 days after hatching but were still dependent on parents. From 1968 to 1987, a total of 44 eggs and 92 nestlings were counted. Mean clutch size was 3.14 ± 1.17 SE (range = 1–5 eggs, n = 14 nests). Hatching success for four nests during the 1972–1973 breeding season was 43.8%. For 14 years in which crude hatching success (nestlings per active nest) could be calculated, 71.6% (43 of 60) of all active nests had at least one nestling. The mean number of nestlings per nest was 2.13 ± 0.71 SE (range = 1–4 nestlings, n = 43 nests). Productivity (the number of nestlings per nest for all active nests) was 1.53. These results were similar to those of two other studies of Jabiru breeding biology conducted in Brazil and Venezuela. Jabiru populations in Belize appear to have increased since the species gained protected status in 1973.
The Blue-winged Macaw (Primolius maracana) has disappeared from most of southern Brazil, Argentina, and Paraguay; its remaining southern stronghold is the 2,179-ha Caetetus Reserve, São Paulo state, Brazil. We estimated the macaw's population inside the reserve (88 individuals) and examined how it and other parrots use the extra-reserve landscape, which is dominated by coffee plantations and pasturelands. Flight activity of the macaw and Scaly-headed Parrot (Pionus maximiliani) declined with distance from Caetetus, although many macaws flew to the vicinity of the reserve to roost. Two other species, Canary-winged Parakeet (Brotogeris versicolurus) and White-eyed Parakeet (Aratinga leucophthalmus), used the landscape independent of the reserve itself. We recorded parrots in 90% of our 1-km2 study plots outside (<12 km) the reserve, but no species was recorded using pasture, coffee or rubber/orange plantations, or scrub habitats, which composed 80% of the landscape around the reserve. Only four habitat types were used by any species. Primary and secondary forests were the habitats most preferred; Eucalyptus plantation habitat was the only totally anthropogenic habitat used. Clearly, protection, and preferably augmentation, of forest cover around Caetetus may be crucial for the macaw's survival at this important site.
Big Quill Lake, Saskatchewan, is an important breeding area for Piping Plovers (Charadrius melodus); the area hosts up to 8% of the continental breeding population, yet little is known about how the site contributes to the overall survival of this species. We studied the reproductive success of Piping Plovers at Big Quill Lake from 1993 to 1995. We located 208 nests and captured and banded 456 young. Nest initiation occurred from mid-May to mid-July, and median nest-initiation dates were 14, 13, and 13 May in 1993, 1994, and 1995, respectively. Mean clutch size for presumed first nests was 3.92 eggs. Nesting success was consistently high from 1993 to 1995, with Mayfield estimates of nest success ranging from 75 to 88%; nests initiated later in the season were less successful than earlier nests. The wide beach (200–1,000 m) at Big Quill Lake may have contributed to high nesting success by reducing efficiency of predators. Use of Big Quill Lake beaches by humans and cattle was also minimal. Fledging success varied dramatically, with 0.02, 1.35, and 1.78 young fledged per breeding pair in 1993, 1994, and 1995, respectively. Low productivity of Piping Plovers in 1993 was a result of low chick survival during a week of rain, cold temperatures, and high winds, rather than low nesting success. Fledging success in 1994 and 1995 was higher than the 1.24 chicks per pair required for population stability on alkaline lakes in the Northern Great Plains. This high productivity suggests that Big Quill Lake is an important Piping Plover breeding site and measures should be taken to ensure its continued protection.
Using field-implanted subcutaneous radio transmitters, we monitored the breeding biology of White-winged Doves (Zenaida asiatica) in a recently colonized urban area (Waco, Texas). We implanted transmitters in June 2002 (n = 39; 16 males, 23 females) and February and March 2003 (n = 40; 17 males, 17 females, 6 unknown sex), and tracked radio-tagged doves every 3rd day until transmitters no longer functioned (90–120 days). We tracked 26 doves to 36 nests in nine tree species. The maximum number of nesting attempts was four. Nest success of first and second nesting attempts was 62 and 24%, respectively, and overall nest success for both years combined was 52%. Mean nest height—as a proportion of tree height—ranged from 0.31 to 0.75. Urban White-winged Doves had an extended breeding season; nesting attempts occurred both before and after the traditional dove breeding period in native brush habitats of the lower Rio Grande Valley of Texas. Field-implantation of subcutaneous radio transmitters was a viable technique for monitoring nesting activities of White-winged Doves.
According to Breeding Bird Survey data, grassland birds are among the most imperiled species in North America. Within this group, grassland owls show steep population declines across the United States. Despite these declines, questions still remain regarding the seasonal and geographic distribution of grassland owls. On San Clemente Island (SCI), California, grassland owls are known to occur, but nothing is known about their distribution or abundance. To increase our understanding of owl populations on SCI, we used night-time spotlighting to survey for grassland owls from October 2001 to October 2002. We recorded 733 detections of three species of owls: Barn Owl (Tyto alba), Burrowing Owl (Athene cunicularia), and Short-eared Owl (Asio flammeus). Barn (8.3 ± 0.8 owls/hr) and Burrowing owls (2.2 ± 0.7 owls/hr) were the most frequently detected species, whereas Short-eared Owls were rarely detected (0.2 ± 0.1 owls/hr). We detected owls during all nighttime hours surveyed and detected Barn Owls in every month of the study. We detected Burrowing Owls only from October to March and Short-eared Owls from December to April, suggesting that they are winter visitors. Despite the bias of increased detectability using roadside surveys, spotlighting from a vehicle enabled us to efficiently cover a large proportion of the island (compared to walking surveys) and survey multiple grassland species using one survey technique.
While banding Cactus Ferruginous Pygmy-Owls (Glaucidium brasilianum cactorum) in Arizona, we removed three Protocalliphora sialia (Diptera: Calliphoridae) from the wing margin of one nestling. Subsequent inspection of nest material revealed an additional 119 Hesperocimex sonorensis (Hemiptera: Cimicidae), another hematophagous parasite. All nestlings (n = 3) fledged successfully, but on day 8 postfledging, two fledglings were found dead and one was missing. Although unsubstantiated, the subclinical effect (e.g., anemia) of these hematophagous parasites may have contributed to the fledglings' demise. This is the first published record of P. sialia parasitizing Ferruginous Pygmy-Owls and the first documented infestation of H. sonorensis for nesting Ferruginous Pygmy-Owls.
Differing intensities of predation pressure can affect the evolution of life history traits in island and mainland populations. We found extremely low nesting success in an insular subspecies of the Varied Tit (Parus varius namiyei; Kozushima Island), and we compared certain life history traits among three subspecies of P. varius experiencing different predation pressures. The nesting success of P. v. namiyei was extremely low as a result of significant nest predation and nest abandonment; 83% of active nests failed due to snake predation. The proportion of depredated nests was significantly greater on Kozushima Island than on Miyakejima Island (P. v. owstoni) or on the mainland (P. v. varius). Of the three subspecies, P. v. namiyei had the longest incubation period, shortest nestling period, an intermediate clutch size, and a small brood size. There were no differences in the date of egg laying among the three populations. The short nestling period for P. v. namiyei may be an adaptive response, as the predation risk during the nestling period on Kozushima was extremely high.
We report the first record of Bronzed Cowbird (Molothrus aeneus) parasitism on the Great-tailed Grackle (Quiscalus mexicanus), which represents the 96th known host for this cowbird species. The record is based on a parasitized clutch, collected from Sinaloa, Mexico, in the collection at the Western Foundation of Vertebrate Zoology. The clutch contained four grackle eggs and one Bronzed Cowbird egg. This record is unusual because the Great-tailed Grackle is extremely intolerant of foreign eggs, ejecting them from their nests almost immediately. As the Bronzed Cowbird expands its range and is studied in greater depth, more hosts will undoubtedly be recorded.
A male Eastern Phoebe (Sayornis phoebe) was found dead on 15 April 2004, hanging from a piece of monofilament fishing line over the Kinnikinic River near River Falls, Wisconsin (Pierce County). The individual was hooked through the tongue by a fly-fishing lure. Although fishing tackle has been reported as a cause of mortality for several aquatic bird species, further research is needed to determine whether abandoned trout-fishing lures represent a significant threat to aerial insectivores.
We report the first record of blow flies (Protocalliphora) parasitizing Swainson's Warblers (Limnothlypis swainsonii). Eight of 12 (67%) nests collected in southeastern Oklahoma during four breeding seasons (2001–2004) were parasitized by P. deceptor larvae. Because Swainson's Warbler is considered a species of high conservation priority in the southeastern United States, and because Protocalliphora can have negative impacts on their hosts, factors influencing blow fly parasitism of this species warrant further investigation.
Little is known about the biology of the Great Spotted Cuckoo (Clamator glandarius) in Israel. After erecting nest boxes intended for cavity-nesting raptors, however, we had opportunities to observe Great Spotted Cuckoos parasitizing Eurasian Jackdaws (Corvus monedula) that also nested in some of the boxes. During the 2003 breeding season, we monitored seven jackdaw nests, six of which were parasitized by cuckoos. In five of the jackdaw nests, one to four cuckoo eggs hatched, and one to three nestlings survived to fledge (four nests). This is the first documentation of Great Spotted Cuckoos parasitizing jackdaws in Israel.
On 25 May 2002, we observed a House Wren (Troglodytes aedon) eating a juvenile house gecko (Hemidactylus frenatus) in Golfito, Costa Rica. Just a few studies report insect-eating birds taking vertebrate prey, and we found no prior publications for this species. The recently introduced house gecko may be a new potential food resource for other native species in Costa Rica and elsewhere.