Central–periphery gradient of individual quality within a colony of Black‐headed Gulls

Abstract

Central nesting sites within avian colonies are often more profitable in terms of fitness, as they can offer better protection against predators compared with colony edges. Thus, central sites are expected to attract high‐quality individuals, which should produce a clear central–periphery gradient in the phenotypic quality of nesting individuals and reproductive output within colonies. The aim of this study was to assess spatial patterns of individual quality within a colony of a common larid, the Black‐headed Gull Chroicocephalus ridibundus. We found that laying was advanced in the central zone of the colony when compared with the periphery, and central pairs tended to lay larger eggs and had higher hatching success than peripheral pairs. Centrally nesting individuals had higher blood haemoglobin concentrations, size‐corrected body mass and heterozygosity (males only), indicating their better condition and higher genetic quality. In contrast, central females had lower plasma albumin concentration, which could possibly be attributed to their greater investment in egg production. Finally, pairs breeding in the central zone of the colony had an elevated heterophil/lymphocyte ratio, suggesting that social stress can be recognized as an important cost of nesting in dense aggregations. The results provide empirical support for central–periphery gradients in the individual quality of colonially nesting Black‐headed Gulls, indicating that spatial gradients in pair quality should be carefully taken into account when conducting research on colonial birds.

Prevalence and Antibiotic Resistance of Campylobacter spp. in Urban and Rural Black-Headed Gulls Chroicocephalus ridibundus

“…While studying black-headed gulls in rural areas (Kusowo), we noted that almost all individuals infected with Campylobacter (97.1%) located their nests at the periphery of the breeding colony. This corresponds with results of our earlier studies in the same colony, where we found evidence for higher physiological condition of birds breeding in the colony centre (Indykiewicz et al 2018b). Thus, it seems likely that central pairs may also be more resistant to pathogens than peripheral low-quality pairs.…”

Melanin-based plumage ornamentation signals condition and physiological stress in the Black-headed Gull

“…After removing outliers, the H/L ratio distribution remained right skewed (skewness = 1.37) and was, thus, log transformed to improve normality. The repeatability of the H/L ratio was relatively high (R = 0.81, P < 0.001), as assessed through independent measurements of the same smears prepared for 25 individuals captured in previous seasons (Indykiewicz et al 2019b). Although leucocyte profiles (and possibly some other physiological traits, e.g.…”

Density-dependence of nestling immune function and physiological condition in semi-precocial colonial bird: a cross-fostering experiment

“…The elevated social stress is recognized as a possible cost of avian coloniality [ 14 ]. Consistently with this hypothesis, it has been shown in black-headed gull that birds nesting in central colony area (areas of higher nest density) are affected by stronger social stress, as indicated by elevated heterophile/lymphocyte (H/L) ratios [ 36 ]. In general, changes in H/L ratios are induced by exposure to external stressor (e.g.…”

“…In general, birds nesting in more attractive, high-density areas are expected to be of higher phenotypic and genetic quality [ 13 , 49 ], which can have a positive effect on the quality of offspring. In fact, central areas of black headed gull colonies were previously shown to be occupied by adult birds with higher blood haemoglobin concentration and higher size-corrected body mass, indicating their better individual quality in terms of body condition [ 36 ]. The artificial reduction of colony size in herring gull Larus argentatus resulted in improvement of body condition of the breeders [ 50 ], which shows constraint inflicted by competition with conspecifics.…”