Observer effects on Common Goldeneye nest defense

Article Abstract:

A study was conducted on observer effects on the nest defense behavior of a nest-box population of incubating Common Goldeneyes. Results showed that female birds increased nest defense during incubation, suggesting that nest defense increases as young became more valuable. The intensity of nest defense behavior, however, varied considerably among females, except during the final six days of incubation. Results were interpreted in terms of a modified version of the positive reinforcement theory of Knight and Temple, where the increase in defense behavior was seen to result from the birds' ability to recognize humans as serious threats to their clutch after repeated visits.

Behavior, Ducks, Human-animal relationships, Agonistic behavior in animals, Animal agonistic behavior, Animal defenses

---

Differential reproductive success of Brown-headed Cowbirds with Northern Cardinals and three other hosts

Article Abstract:

Northern Cardinals (Cardinalis cardinalis) are less adequate as hosts for Brown-headed Cowbirds (Molothrus ater) compared to three other hosts: Song and Chipping Sparrows and Yellow Warblers. Cowbirds are found in 11 out of 63 broods fledged by cardinals, compared to 62 out of 93 broods by the other hosts. Features such as the larger size of and the short incubation time for the cardinal eggs as well as the small size of cardinal clutches influence the growth rate of cowbird nestlings. The resulting differences in body mass are higher when the cowbirds hatch after the cardinals. Cowbirds reared without cardinal nestmates grow well.

Nestlings, Parasitic birds

---

Egg-eating by female Brown-headed Cowbirds

Article Abstract:

A study of the female Brown-headed Cowbird (Molothrus ater) was conducted to estimate how many eggs and nestlings it ate after removing them from host nests. Field studies were conducted to calculate the proportion of removed eggs that were found, uneaten, under host nests. These studies, supplemented by earlier findings, showed that despite the high nutritional value of the eggs, cowbirds consume only 40% of the eggs they remove. Explanations for this behavior have been discussed and it has been suggested that cowbirds do not remove eggs for food alone.

Food and nutrition

Similar abstracts:

• Abstracts: Effect of conventional and organic production practices on the prevalence and antimicrobial resistance of Campylobacter spp. in poultry
• Abstracts: Effects of mate removal on incubation behavior and reproductive success of female Wood Ducks. Patterns of nest attendance in female Wood Ducks
• Abstracts: Genetic differentiation of oak populations within Quercus robur/Quercus petraea complex in Central and Eastern Europe
• Abstracts: Evidence for the presence of an alternative glucose transport system in Clostridium beijerinckii NCIMB 8052 and the solvent-hyperproducing mutant BA101
• Abstracts: Components of an SCF ubiquitin ligase localize to the centrosome and regulate the centrosome duplication cycle

This website is not affiliated with document authors or copyright owners. This page is provided for informational purposes only. Unintentional errors are possible.