title: Effects of population size on singing behavior of a rare duetting songbird

authors: Valderrama Ortiz, Sandra Viviana

subjects: behavioral conservation

abstract: Although the genetic and ecological effects of population declines in endangered species have been well studied, little is known of the social consequences. Changes in signaling behavior may result in disrupted communication and affect both reproductive and conflict-resolution activities. The North Island Kōkako (Callaeas wilsoni) is an endangered, duetting (i.e., alternating, coordinated singing by mated pairs) songbird endemic to New Zealand temperate rain forests. Scattered populations (approximately 1500 individuals in 13 surviving and 11 translocated populations) in isolated conservation areas of different sizes have been rescued from extirpation and are currently recovering. We examined key song attributes of the Kōkako to assess whether population size or growth rate are related to song complexity, the reduction of which may compromise effective communication. We analyzed song repertoire size and phrase-type sharing (i.e., Jaccard index of similarity), vocal performance (singing rates, song switching rates, and diversity of phrase types), and song syntactical characteristics (i.e., unpredictability in sequences of phrase types) in surviving and translocated populations (populations of approximately 19–250 territorial individuals). Population size was positively correlated with a population's song repertoire, song diversity, and switching of song phrase types and negatively correlated with shared phrase types and variation in syntactical structure of songs. Population growth rate correlated positively with pair repertoire size, population repertoire size, and singing rates during song bouts. As for solo-singing species in fragmented landscapes, songs in the fragmented populations of Kōkako appear to be undergoing microevolution as occurs in island colonization events. Our results suggest that vocal changes in small populations could affect population establishment and growth, particularly in multiple-source translocations. We believe measurement of vocal behavior could be used as a supplement to periodic population censuses to allow more frequent monitoring of population size.

text: Effects of population size on singing behavior of a rare duetting songbird Although the genetic and ecological effects of population declines in endangered species have been well studied, little is known of the social consequences. Changes in signaling behavior may result in disrupted communication and affect both reproductive and conflict-resolution activities. The North Island Kōkako (Callaeas wilsoni) is an endangered, duetting (i.e., alternating, coordinated singing by mated pairs) songbird endemic to New Zealand temperate rain forests. Scattered populations (approximately 1500 individuals in 13 surviving and 11 translocated populations) in isolated conservation areas of different sizes have been rescued from extirpation and are currently recovering. We examined key song attributes of the Kōkako to assess whether population size or growth rate are related to song complexity, the reduction of which may compromise effective communication. We analyzed song repertoire size and phrase-type sharing (i.e., Jaccard index of similarity), vocal performance (singing rates, song switching rates, and diversity of phrase types), and song syntactical characteristics (i.e., unpredictability in sequences of phrase types) in surviving and translocated populations (populations of approximately 19–250 territorial individuals). Population size was positively correlated with a population's song repertoire, song diversity, and switching of song phrase types and negatively correlated with shared phrase types and variation in syntactical structure of songs. Population growth rate correlated positively with pair repertoire size, population repertoire size, and singing rates during song bouts. As for solo-singing species in fragmented landscapes, songs in the fragmented populations of Kōkako appear to be undergoing microevolution as occurs in island colonization events. Our results suggest that vocal changes in small populations could affect population establishment and growth, particularly in multiple-source translocations. We believe measurement of vocal behavior could be used as a supplement to periodic population censuses to allow more frequent monitoring of population size.

year: 2013

title: Global beta-diversity of angiosperm trees is shaped by Quaternary climate change

authors: Xu, W-B

subjects: Humans

abstract: As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.

text: Global beta-diversity of angiosperm trees is shaped by Quaternary climate change As Earth's climate has varied strongly through geological time, studying the impacts of past climate change on biodiversity helps to understand the risks from future climate change. However, it remains unclear how paleoclimate shapes spatial variation in biodiversity. Here, we assessed the influence of Quaternary climate change on spatial dissimilarity in taxonomic, phylogenetic, and functional composition among neighboring 200-kilometer cells (beta-diversity) for angiosperm trees worldwide. We found that larger glacial-interglacial temperature change was strongly associated with lower spatial turnover (species replacements) and higher nestedness (richness changes) components of beta-diversity across all three biodiversity facets. Moreover, phylogenetic and functional turnover was lower and nestedness higher than random expectations based on taxonomic beta-diversity in regions that experienced large temperature change, reflecting phylogenetically and functionally selective processes in species replacement, extinction, and colonization during glacial-interglacial oscillations. Our results suggest that future human-driven climate change could cause local homogenization and reduction in taxonomic, phylogenetic, and functional diversity of angiosperm trees worldwide.

year: 2023-04-05

title: Mainstreaming managed retreat in Aotearoa New Zealand [Policy Brief]

authors: Hanna, Christina Jane

abstract: Retreat in Aotearoa has evolved from early indigenous practices which saw relocation from harm as a viable option, to the onset of colonisation and more protection-based approaches, to more passive policy that acknowledged the option of retreat but provided little guidance or implementation support, to today, when retreat is becoming a strategic part of our national risk management framework.

text: Mainstreaming managed retreat in Aotearoa New Zealand [Policy Brief] Retreat in Aotearoa has evolved from early indigenous practices which saw relocation from harm as a viable option, to the onset of colonisation and more protection-based approaches, to more passive policy that acknowledged the option of retreat but provided little guidance or implementation support, to today, when retreat is becoming a strategic part of our national risk management framework.

year: 2023-04