Heuglin's Gull (L. heuglini / antelius)

(last update: 26-2-2014)

Number of Primaries with Black Pigmentation.

The graph below illustrates the overlap in number of primaries showing black markings. Only on average there is more black in heuglini.

Figure above: Number of Primaries with Black Pigmentation.

The average number of primaries with black pigmentation in Lesser Black-backed Gull was 6.9 (SD 0.61, n = 931), and the sex difference was just significant (Mann-Whitney U = 100938, Z = -1.992, P = 0.046, male n = 433, female n = 498). In Lesser Black-backed Gull too, the number of primaries with black is age-related, when sub-adults are compared to known-age adults (sub-adults: mean 7.2, SD 0.68; adults: mean 6.7, SD 0.64, Mann-Whitney U = 1000, Z = -4.071, P < 0.001, sub-adult n = 62, adult n = 53. See table 4 below). However, we found some exceptions, as older birds like 10cy LBBG o67, 12cy LBBG yET, 12cy LBBG o65 showed 8 and even 9 primaries with black. When sub-adults (62 birds, of which 70% are males) are excluded from the analysis, the difference between the sexes is no longer significant (Mann-Whitney U = 89591, Z = -1.294, P = 0.196, male n = 390, female n = 480).

Table 3: Number of primaries with black pigmentation in Herring and Lesser Black-backed Gulls. Values are %.

Table 4: Number of primaries with black pigmentation in Lesser Black-backed Gulls of known age (ringed as pullus).

Number of primaries showing black in breeding LBBG.