• Conditional female strategies influence hatching success in a communally nesting iguana

      Moss, Jeanette B.; Gerber, Glenn P.; Laaser, Tanja; Goetz, Matthias; Oyog, TayVanis; Welch, Mark E. (2020)
      The decision of females to nest communally has important consequences for reproductive success. While often associated with reduced energetic expenditure, conspecific aggregations also expose females and offspring to conspecific aggression, exploitation, and infanticide. Intrasexual competition pressures are expected to favor the evolution of conditional strategies, which could be based on simple decision rules (i.e., availability of nesting sites and synchronicity with conspecifics) or on a focal individual's condition or status (i.e., body size). Oviparous reptiles that reproduce seasonally and provide limited to no postnatal care provide ideal systems for disentangling social factors that influence different female reproductive tactics from those present in offspring‐rearing environments. In this study, we investigated whether nesting strategies in a West Indian rock iguana, Cyclura nubila caymanensis, vary conditionally with reproductive timing or body size, and evaluated consequences for nesting success. Nesting surveys were conducted on Little Cayman, Cayman Islands, British West Indies for four consecutive years. Use of high‐density nesting sites was increasingly favored up to seasonal nesting activity peaks, after which nesting was generally restricted to low‐density nesting areas. Although larger females were not more likely than smaller females to nest in high‐density areas, larger females nested earlier and gained access to priority oviposition sites. Smaller females constructed nests later in the season, apparently foregoing investment in extended nest defense. Late‐season nests were also constructed at shallower depths and exhibited shorter incubation periods. While nest depth and incubation length had significant effects on reproductive outcomes, so did local nest densities. Higher densities were associated with significant declines in hatching success, with up to 20% of egg‐filled nests experiencing later intrusion by a conspecific. Despite these risks, nests in high‐density areas were significantly more successful than elsewhere due to the benefits of greater chamber depths and longer incubation times. These results imply that communal nest sites convey honest signals of habitat quality, but that gaining and defending priority oviposition sites requires competitive ability.
    • Effects of inbreeding and parental incubation on captive breeding success in Hawaiian crows

      Hoeck, Paquita E. A.; Wolak, Matthew E.; Switzer, Richard A.; Kuehler, Cyndi M.; Lieberman, Alan A. (2015)
      We used 17 years of captive breeding records of the Hawaiian crow (Corvus hawaiiensis) to study the effects of individual and parental level of inbreeding on survival through early life…. Our study contributes to evidence that the strength of inbreeding depression is particularly severe in early life traits. It shows that the negative effects of inbreeding on reproductive success should be accounted for even in benign captive environments where survival is maximized and suggests that parental incubation should be favored over artificial incubation in avian captive breeding programs.
    • Inter-aviary distance and visual access influence conservation breeding outcomes in a territorial, endangered bird

      Flanagan, Alison M.; Rutz, Christian; Farabaugh, Susan M.; Greggor, Alison L.; Masuda, Bryce M.; Swaisgood, Ronald R. (2020)
      Species extinctions are becoming a global crisis, affecting biodiversity and ecosystem services, with island populations being particularly vulnerable. In response, conservation managers are increasingly turning to ex situ conservation breeding programs to establish assurance populations and provide a source for release and re-establishment of wild populations. The 'Alalā (Hawaiian crow, Corvus hawaiiensis) is a critically endangered and territorial island corvid that became extinct in the wild in 2002, following a severe and prolonged population decline during the late 20th century....