The long and short of it: converting between maximum and minimum tarsus measurements in passerine birds

Caravaggi, Anthony; Bayley, Sam; Facey, Richard J.; Hera, Iván de la; Shewring, Mike P.; Smith, Jez A.

doi:10.1080/03078698.2022.2050937

Cited by 2 publications

(1 citation statement)

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“…50 days old, they were ringed with a permanent BTO metal ring on one leg and an alpha-numeric coded blue plastic colour ring on the other. Prior to release, each chick was weighed, measured for minimal tarsus length ( Caravaggi et al, 2021 ), head length (measured from the back of the skull to the tip of the upper mandible), bill length (from the tip of upper mandible to where the base of the upper mandible meets feathers) and bill depth (measured at the gonys angle on the bill) and scored for aggression (number of bites/pecks received by handler during ringing).…”

Section: Methodsmentioning

confidence: 99%

Early-life diet does not affect preference for fish in herring gulls (Larus argentatus)

Inzani,

Kelley,

Thomas

et al. 2024

PeerJ

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Urban populations of herring gulls (Larus argentatus) are increasing and causing human-wildlife conflict by exploiting anthropogenic resources. Gulls that breed in urban areas rely on varying amounts of terrestrial anthropogenic foods (e.g., domestic refuse, agricultural and commercial waste) to feed themselves. However, with the onset of hatching, many parent gulls switch to sourcing more marine than anthropogenic or terrestrial foods to provision their chicks. Although anthropogenic foods may meet chick calorific requirements for growth and development, some such foods (e.g., bread) may have lower levels of protein and other key nutrients compared to marine foods. However, whether this parental switch in chick diet is driven by chicks’ preference for marine foods, or whether chicks’ food preferences are shaped by the food types provisioned by their parents, remains untested. This study tests whether chick food preferences can be influenced by their provisioned diet by experimentally manipulating the ratio of time for which anthropogenic and marine foods were available (80:20 and vice versa) in the rearing diets of two treatment groups of rescued herring gull chicks. Each diet was randomly assigned to each of the 27 captive-reared chicks for the duration of the study. We tested chicks’ individual food preferences throughout their development in captivity using food arrays with four food choices (fish, cat food, mussels and brown bread). Regardless of the dietary treatment group, we found that all chicks preferred fish and almost all refused to eat most of the bread offered. Our findings suggest that early-life diet, manipulated by the ratio of time the different foods were available, did not influence gull chicks’ food preferences. Instead, chicks developed a strong and persistent preference for marine foods, which appears to match adult gulls’ dietary switch to marine foods upon chick hatching and may reinforce the provisioning of marine foods during chick development. However, whether chicks in the wild would refuse provisioned foods, and to a sufficient extent to influence parental provisioning, requires further study. Longitudinal studies of urban animal populations that track wild individuals’ food preferences and foraging specialisations throughout life are required to shed light on the development and use of anthropogenic resource exploitation.

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Section: Methodsmentioning

confidence: 99%