Cotinga 38 Short Communications Tw of Graaia gatiani Published descriptions of Grallaria (Grallariidae) eggs are all relatively consistent, usually described as some shade of blue, with few or no 7 markings . Scaled Antpitta G. 8 guatimalensis is no exception , with the following published records: pale blue (nominate5,6); deep blue or ‘robin’s-egg blue’ (G. g. ochraceiventris18; nominate19); 24 22 blue-green (nominate ; ssp.? ); turquoise-blue (G. g. regulus3,4); or simply blue (ssp.?17). Rowley’s18,19 eggs were described as ‘bluish’ 98 Cotinga 38 Short Communications cup was 14 cm tall, but only 3.5 cm tall at the upper end. Overall external diameter was 22 cm, with the overhanging portions being supported by epiphytic vegetation. The internal measurements of the cup were 9.5 wide by 6.5 deep. The bulky cup was formed primarily of humid leaves and small sticks, with a rather loose internal cup of dark rootlets. Apart from the white eggs, the nests described here are largely similar to those described from elsewhere in the species’ range7,8. Naturalists have been puzzled by the widespread occurrence of blue-pigmented eggs across the avian phylogeny for many years, especially given their apparent obviousness to predators. Adaptive hypotheses for blue eggs proposed in the past include thermoregulation1, aposematism23, crypsis12 and egg recognition20. One relatively new hypothesis that has acquired some support, is sexual- signaling hypothesis9,15, which postulates that egg coloration is a reliable signal of female quality because the pigments responsible for blue-green shell pigments (biliverdins) are valuable antioxidents11, and only healthy females should be able to afford iur st an s o Sca ntitta Grallaria guatimalensis in southst to include biliverdins in their cuaor shoin immacuat hit s aro rn eggshells during the stressful process of egg formation. The debate continues, however, and 10 by Howell & Webb , but equally HFG found the second clutch has spawned a rich literature subjective observations by HFG (G. g. regulus) on 5 March 2014 at exploring, among other aspects, of photographs and museum the Utuana Reserve of the Jocotoco the sources of dietary anti-oxidants specimens suggest that, across Foundation, prov. Loja, Ecuador and their effect on the deposition its range, the Scaled Antpitta (79º45’W 04º22’S; 2,600 m). As of biliverdins in eggshells, the lays blue eggs which may or so few nests of grallariids are heritability of eggshell coloration, 7 may not vary strongly in hue. described , both the nest, and the the nature of the signals that blue Here we describe two clutches two-egg clutch, are described below. eggs convey to mates, and the observed in situ that represent the Like the Mexican clutch described effect of egg coloration on male first reports of Scaled Antpittas above, both eggs were immaculate parental care2,13–16,21,26. With so (or any Grallaria) laying white (Fig. 1). They measured 31.6 few clutches known for Grallaria unpigmented eggs. × 25.0 mm and 30.7 × 25.0 mm antpittas, it remains to be seen if RVH found the first clutch and weighed 10.7 g and 10.2 g, variation in blue pigmentation is (nominate guatimalensis) on respectively. The open-cup nest more widespread than currently 9 August 2008 at San Juan, was 1.6 m above ground on top of a known, and if potential variation Huazalingo, Hidalgo, Mexico c.45º angled log, 15 cm in diameter. in the intensity of blue coloration (20°59’N 98°30’W; 1,260 m). Details It was nestled into the ample ferns may play a role in sexual signaling of the nest location have been and bromeliads growing on the or parental care in these poorly 25 published previously , but the eggs log and, due to the angled nature studied Neotropical birds. were not described. This clutch, of of the substrate, was considerably the nominate subspecies, comprised taller at the lower end to create Acknowledgements two immaculate white eggs, but no a level nest rim and even cup. HFG thanks Field Guides measurements were taken. Externally, at the lower end, the Inc., John V. & the late Ruth 99 Cotinga 38 Short Communications Ann Moore, Matt Kaplan, the (2013) Scaled Antpitta 17. Nehrkorn, A. (1914) Nachträge Population Biology Foundation, the (Grallaria guatimalensis). zu Nehrkorn’s Eierkatalog. Jocotoco Foundation, and Cabañas In: Schulenberg, T. S. Belin: R. Friedländer & San Isidro for supporting his field (ed.) Neotropical Birds Sohn. work. The staff of Utuana and Online. Ithaca: Cornell 18. Rowley, J. S. (1966) Breeding Jorupe lodges facilitated access Lab of Ornithology. http:// records of birds of the Sierra to Jocotoco Foundation reserves neotropical.birds.cornell.edu/ Madre del Sur, Oaxaca, and Mort Isler provided useful portal/species/overview?p_p_ Mexico. Proc. West. Found. comments on the submitted draft. spp=402441 (accessed 15 Vert. Zool. 1: 107–204. October 2015). 19. Rowley, J. S. (1984) Breeding References 9. Hanley, D., Heiber, G. & records of land birds in 1. Bakken, G. S., Vanderbilt, V. Dearborn, D. C. (2008) Oaxaca, Mexico. Proc. West. C., Buttuttuttermer, W. A. & Testing an assumption of the Found. Vert. Zool. 2: 73–224. Dawson, W. R. 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Received 12 September 2015; final revision accepted 3 December 2015; published online 25 February 2016 101.