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aaia gatiani Published descriptions of (Grallariidae) eggs are all relatively consistent, usually described as some shade of blue, with few or no markings7. Scaled 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’

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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, 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 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, 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 . were not described. This clutch, of of the substrate, was considerably the nominate subspecies, comprised taller at the lower end to create 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

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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 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. (1978) Avian sexual-signaling hypothesis: 20. Soler, J. J. & Møller, A. eggs: thermoregulatory value does blue-green egg color P. (1996) A comparative of very high near-infrared reflect maternal antioxidant analysis of the evolution of reflectance. Science 200: capacity? Condor 110: variation in appearance of 321–323. 767–771. eggs of European 2. Cassey, P., Thomas, G. H., 10. Howell, S. N. G. & Webb, S. in relation to brood Portugal, S. J., Maurer, G., (1995) A guide to the birds of parasitism. Behav. Ecol. 7: Hauber, M. E., Grim, T., Mexico and northern Central 89–94. Lovell, P. G. & Miksik, I. America. Oxford: Oxford 21. Soler, J. J., Moreno, J., (2012) Why are birds’ eggs University Press. Aviles, J. M. & Møller, A. colourful? Eggshell pigments 11. Kennedy, G. Y. & Vevers, H. P. (2005) Blue and green co-vary with life-history G. (1976) A survey of avian egg-color intensity is and nesting ecology eggshell pigments. Comp. associated with parental among British breeding Biochem. Physiol. B 55: effort and mating system in non- birds. Biol. J. 117–123. passerines: support for the Linn. Soc. 106: 657–672. 12. Lack, D. (1958) The sexual selection hypothesis. 3. Dobbs, R. C., Martin, P. R., significance of the colour Evolution 59: 636–644. Batista, C., Montag, H. of turdine eggs. Ibis 100: 22. Stiles, F. G. & Skutch, A. F. & H. F. Greeney, H. F. 145–166. (1989) A guide to the birds (2003) Notes on egg-laying, 13. Morales, J., Kim, S. Y., of . Ithaca, NY: incubation and nestling Lobato, E., Merino, S., Cornell University Press. care in the Scaled Antpitta Tomás, G., Martínez-de la 23. Swynnerton, C. F. M. (1916) Grallaria guatimalensis. Puente, J. & Moreno, J. On the coloration of mouths Cotinga 19: 65–70. (2010) On the heritability and eggs of birds. Ibis 58: 4. Dobbs, R. C., Martin, P. R. of blue-green eggshell 264–294. & Kuehn, M. J. (2001) On coloration. J. Evol. Biol. 23: 24. del Toro, A. A. (1971) Las the nest, eggs, nestlings, 1783–1791. aves de Chiapas. Tuxtla and parental care of the 14. Morales, J., Velando, A. & Gutierrez: Universidad Scaled Antpitta (Grallaria Moreno, J. (2008) Pigment Autónoma de Chiapas. guatimalensis). Orn. Neotrop. allocation to eggs decreases 25. Valencia-Herverth, R., 12: 225–233. plasma antioxidants in Valencia-Herverth, J., 5. Edwards, E. P. (1967) Nests of a songbird. Behav. Ecol. Calderón, R. P., Nochebuena, the Common Bush-Tanager Sociobiol. 63: 227–233. M. O., Hernández, R. H. & and the Scaled Antpitta. 15. Moreno, J. & Osorno, J. Nochebuena, M. O. (2012) Condor 69: 605. L. (2003) Avian egg colour Información adicional sobre 6. Edwards, E. P. & Lea, R. and sexual selection: does la avifauna de Hidalgo, B. (1955) Birds of the eggshell pigmentation México. Huitzil 13: 95–103. Monserrate area, Chiapas, reflect female condition and 26. Walters, L. A. & Getty, Mexico. Condor 57: 31–54. genetic quality? Ecol. Lett. 6: T. (2010) Are brighter 7. Greeney, H. F., Dobbs, R. C., 803–806. eggs better? Egg color and Martin, P. R. & Gelis, R. A. 16. Navarro, C., Perez- parental investment by (2008) The breeding biology Contreras, T., Aviles, J. House Wrens. J. Field Orn. of Grallaria and Grallaricula M., McGraw, K. J. & Soler, 81: 155–166. antpittas. J. Field Orn. 79: J. J. (2011) Blue-green 113–129. eggshell coloration reflects Harold F. Greeney 8. Greeney, H. F., Rivera- yolk antioxidant content in Yanayacu Biological Station Ortíz, A., Rodríguez-Flores, Spotless Starlings Sturnus & Center for Creative Studies, C., Soberanes-González, unicolor. J. Avian Biol. 42: Cosanga, Napo, Ecuador; c/o 721 C. & Arizmendi, M. C. 538–543.

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Foch & Amazonas, Quito, Ecuador. E-mail: [email protected].

Raúl Valencia-Herverth Instituto Tecnológico de Huejutla. Km 5.5 carretera Huejutla– Chalahuiyapa, AP 94, Huejutla de Reyes, Hidalgo, 43000, México.

Received 12 September 2015; final revision accepted 3 December 2015; published online 25 February 2016

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