Insects found in birds’ nests from Argentina. Furnarius rufus (Gmelin, 1788) (Aves: Furnariidae) and their inquiline birds, the true hosts of Acanthocrios furnarii (Cordero & Vogelsang, 1928) (Hemiptera: Heteroptera: Cimicidae)

The nest of Furnarius rufus (Gmelin, 1788) [Aves: Furnariidae] is a domed mud structure, with a partition separating the breeding chamber from the outside. In general each couple builds one nest per year, but each nest is used for one clutch or two consecutive clutches in the same breeding season. Some nests can remain in the field for 2 or 3 years, but some had a longer permanence (up to more than 8 years). Thus the nests are widely used by other vertebrate inquilines. Insects found in nests of F. rufus mentioned in the literature belong to Coleoptera [Chrysomelidae (1 sp.), Histeridae (1 sp.)], Hemiptera [Cimicidae (1 sp.), Reduviidae: Triatominae (1 sp.)], Hymenoptera [Apidae: Meliponinae (1 sp.)], and Diptera [Muscidae (2 spp.)]. A total of 9 orders, 35 families (two unidentified), and 67 species of insects (including 14 identified to genus and 10 undetermined), were found in 251 nests of F. rufus sampled in Argentina (Chaco [6], Córdoba [14], Santa Fe [2], Entre Ríos [7], San Luis [1], La Pampa [12], and Buenos Aires [209]). The most abundant species was one hematophagous insect, Acanthocrios furnarii (Cordero & Vogelsang, 1928) [Hemiptera: Cimicidae], an exclusive parasite on the inquiline birds. Agelaioides badius badius (Vieillot, 1819) [Aves: Icteridae], Sicalis flaveola pelzelni Sclater, 1872 [Aves: Emberizidae], and Troglodytes aedon Vieillot, 1809 [Aves: Troglodytidae] are new hosts of A. furnarii. Progne chalybea (Gmelin, 1789) [Aves: Hirundinidae] was found for the first time infested by A. furnarii inside the nests of F. rufus. The insects in the nests of Furnarius cristatus Burmeister, 1888, and those of P. domesticus, Progne sp., S. f. pelzelni, and T. aedon outside the nests of F. rufus were also investigated. Some ticks (Acarina: Argasidae, Ixodidae) found in the nests of F. rufus and P. domesticus are mentioned.

New records of bird species from Ilha Grande, state of Rio de Janeiro, southeastern Brazil

We add 32 new records of species to the existing checklist of birds of the coastal island of Ilha Grande, state of Rio de Janeiro, Brazil. Notably, seven of these species are endemic to the Atlantic Forest. Sporophila falcirostris is globally Vulnerable and Haematopus palliatus is Near Threatened in Brazil. We also report the second record of Agelaioides badius from Rio de Janeiro state. We also compare our species list with lists of birds of Ilhabela and Anchieta islands. While some of the newly recorded species are probably non-resident to Ilha Grande or represent range expansions, most species occur in Rio de Janeiro throughout the year. Thus, our records may be a consequence of the surveying new sites on the island but also recent colonization. Our study increases the number of bird species known to occur on Ilha Grande from 222 to 254, which is one-third of the species reported from Rio de Janeiro state. We recorded 13 species threatened by extinction at regional, national or global levels.

A novel method of rejection of brood parasitic eggs reduces parasitism intensity in a cowbird host

The hosts of brood parasitic birds are under strong selection pressure to recognize and remove foreign eggs from their nests, but parasite eggs may be too large to be grasped whole and too strong to be readily pierced by the host's bill. Such operating constraints on egg removal are proposed to force some hosts to accept parasite eggs, as the costs of deserting parasitized clutches can outweigh the cost of rearing parasites. By fitting microcameras inside nests, we reveal that the Neotropical baywing ( Agelaioides badius ), a host of the screaming cowbird ( Molothrus rufoaxillaris ) and shiny cowbird ( Molothrus bonariensis ), instead circumvents such constraints by kicking parasite eggs out of the nest. To our knowledge, this is the first report of a passerine bird using its feet to remove objects from the nest. Kick-ejection was an all-or-nothing response. Baywings kick-ejected parasite eggs laid before their own first egg and, if heavily parasitized, they ejected entire clutches and began again in the same nest. Few baywings were able to rid their nests of every parasite egg, but their novel ejection method allowed them to reduce the median parasitism intensity by 75 per cent (from four to one cowbird eggs per nest), providing an effective anti-parasite defence.