Fig 1.
Average spectral reflectance of three host species and Asian koel eggs laid in nests of two hosts (common myna and long-tailed shrike; note that house crow was not included due to lack of spectral reflectance data).
We include photographs of koel and host eggs from each species. All photos taken by V.E. Abernathy and M.I. Nahid. CM = common myna (n = 29 eggs from 11 nests), HC = house crow (n = 8 eggs from 3 nests), LTS = long-tailed shrike (n = 26 eggs from 7 nests), AK_CM = Asian koel in common myna nest (n = 5 eggs from 4 nests), AK_HC = Asian koel in house crow nest (not included) and AK_LTS = Asian koel in long-tailed shrike nest (n = 16 eggs from 4 nests). Spectral reflectance was measured at three egg regions, curves denoted by: b = blunt spectral reflectance of the egg, m = middle spectral reflectance of the egg, t = top spectral reflectance of the egg.
Fig 2.
Egg volume and shape of Asian koel (AK) eggs laid in specific host nests (left panels) and eggs of host species (right panel).
Asterisks denotes significant difference among Asian koel eggs and host eggs (see Table 1; N.S. p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001). Host and Asian koel eggs were analyzed separately. Vertical bars depict the 95% confidence interval.
Table 1.
Linear mixed-effects models on egg characteristics (volume, shape and spotting pattern) of Asian koel eggs and three host species (common myna, house crow and long-tailed shrike).
Fig 3.
Egg spotting pattern variables of Asian koel (AK) eggs laid in the nests of three host species (left panel) and two host species (house crow and long-tailed shrike; right panel).
Asterisks denotes significant difference between Asian koels and hosts, respectively, based on linear-mixed effects model outputs (see Table 1; N.S. p > 0.05, *p < 0.05, **p < 0.01, ***p < 0.001). Tests of Asian koel and hosts eggs were performed separately. Vertical bars depict the 95% confidence interval. 1Significant only after log-transformation (see S1 Table).
Fig 4.
Average achromatic and chromatic JNDs ± SD between Asian koel eggs laid in common myna nests (AK_CM) compared to three hosts: The house crow (HC), the common myna (CM) and the long-tailed shrike (LTS) and the eggs of the Asian koel laid in long-tailed shrike nests (AK_LTS).
Achromatic (Achrom_JND) and chromatic (Chrom_JND) analyses were performed for egg regions (B = blunt, M = middle, T = top) and visual system (UVS = ultraviolet-sensitive, VS = violet-sensitive) separately. Letters above columns denote significant differences (Dunn post-hoc test, p < 0.05 after correcting for multiple tests following Benjamini and Hochberg 1995 [94], see S4 Table).
Fig 5.
Average achromatic and chromatic JNDs ± SD between Asian koel eggs laid in long-tailed shrike nests compared to three hosts: The house crow (HC), the common myna (CM) and the long-tailed shrike (LTS) and the eggs of the Asian koel laid in common myna nests (AK_CM).
Achromatic (Achrom_JND) and chromatic (Chrom_JND) analyses were performed for each egg region (B = blunt, M = middle, T = top) and visual system (UVS = ultraviolet-sensitive, VS = violet-sensitive), separately. Letters above columns denote significant differences (Dunn post-hoc test, p < 0.05 after accounting for multiple tests following Benjamini and Hochberg 1995 [94], see supplement for tests S4 Table).
Table 2.
Linear mixed effects model using cone stimulation values of Asian koel eggs as response, and host species (common myna and long-tailed shrike) and in different egg regions (blunt, middle, top) as fixed effects.