Alignment of ordinal and quantitative species abundance and size indices for the detection of shifting baseline syndrome.

Loss of knowledge about historical environmental conditions and species' abundances threatens how new generations potentially perceive their environment and take action. The intergenerational shift in perceptions of environmental thresholds is a phenomenon frequently termed shifting baseline syndrome (SBS). The goals of this study were (1) to determine relationships between ordinal scores (e.g., few, many) and quantitative measures (e.g., estimates of population size) used by members of a Maori community in New Zealand to score indicators for understanding the abundance of forest resources, and (2) to then analyze these relationships according to people's age to detect the effects of SBS and the rate that this shift was occurring for each indicator. We detected consistent relationships between the ordinal scores and quantitative measures for six forest indicators provided by community members. However, there was only a high degree of confidence about the direction of the age effect for three abundance indicators (Kereru [New Zealand Pigeon], Hemiphaga novaeseelandiae, 15% increase [CI = 5.1-27.1%] in flock size for any given ordinal category for each decade increase in age; long-finned eel, Anguilla dieffenbachia, 30% decrease [CI = -45.1% to -11.3%] in the distance (m) walked along a riverbank between observations of an eel for any given ordinal category for each decade increase in age; and Australian brush-tailed possum, Trichosurus vulpecula, 27% decrease [CI = -38.9% to -13.9%] in the distance (m) walked through forest between observations of possum sign for any given ordinal category for each decade increase in age), but the effect was statistically strong for all three. The decoupling of indigenous peoples and local communities (IPLC) from their traditional lands and biodiversity by an array of political, environmental, social and economic drivers and feedback mechanisms have contributed to and exacerbated the conditions for SBS. However, the protection of customary practices to engage with the environment, including the harvest of natural resources, community-based environmental monitoring initiatives, and cultural immersion education programs offer opportunities for IPLC to mitigate the often deleterious effects of SBS.

Age-related reproductive performance of the Adélie penguin, a long-lived seabird exhibiting similar outcomes regardless of individual life-history strategy.

Age-related variation in reproductive performance in long-lived iteroparous vertebrate species is common, with performance being influenced by within-individual processes, such as improvement and senescence, in combination with among-individual processes, such as selective appearance and disappearance. Few studies of age-related reproductive performance have compared the role of these drivers within a metapopulation, subject to varying degrees of resource competition. We accounted for within- and among-individual changes among known-aged Adélie penguins Pygoscelis adeliae during 17 years (1997-2013), at three clustered colonies of disparate size, to understand patterns in age-related reproductive success during early and late adulthood. Age at first reproduction (AFR) was lowest, and number of breeding attempts highest, at the largest colony. Regardless of AFR, success improved with early post-recruitment experience. For both oldest and youngest recruitment groups, peak performance occurred at the end of their reproductive life span indicating a possible cost of reproduction. Intermediate recruitment groups reached peak performance in their mid-reproductive life span and with intermediate breeding experience, before decreasing. Breeding success was lowest for the initial breeding attempt regardless of AFR, but we observed subsequent variation relative to recruitment age. Gaining experience by delaying recruitment positively influenced reproductive performance early in the reproductive life span and was most evident for the youngest breeders. Oldest recruits had the highest initial and peak breeding success. Differences in AFR resulted in trade-offs in reproductive life span or timing of senescence but not in the overall number of breeding attempts. Patterns differed as a function of colony size, and thus competition for resources. Early life improvement in performance at the larger colonies was primarily due to within-individual factors and at the largest colony, AFR. Regardless of colony size late-life performance was positively related to the age at last reproduction, indicating selective disappearance of lower performing individuals. These results highlight that different life-history strategies were equally successful, indicating that individuals can overcome potential trade-offs associated with early- and late-life performance. These results have important implications for understanding the evolution of life-history strategies responsible for driving population change.

Complementarity of indigenous and western scientific approaches for monitoring forest state.

Cross-cultural environmental monitoring systems inform on a broad suite of indicators relevant to both scientific and local communities. In this study, we used forest-plot-based survey measures developed by western scientists and a set of community-based survey indicators developed by Maori, the indigenous people of New Zealand (NZ), to compare the current state of two ecologically congruent forests (Whirinaki and Ruatahuna), as they related to a historic Ruatahuna forest state (Baseline; 1955-1975) in NZ. Both the plot-based and community-based field surveys indicated that the Whirinaki forest was in a better state than the Ruatahuna forest. This was supported by a stronger mauri (concept of life essence) rating assigned by Maori elders to the Whirinaki forest compared with the Ruatahuna forests. However, both the Ruatahuna and Whirinaki forests were deemed to be in a significantly poorer state than the Baseline forest. A cross-cultural monitoring system provides understanding of forest state that both managers and communities can use for decision-making. Historical baselines of forest state can provide ecological targets for restoration initiatives and also identify where on the restoration continuum current forest indicators lie. The alignment of plot-based measures with community-based indicators offers possibilities for future-proofing a cross-cultural monitoring system and buffering it from intergenerational shifts in ecological baselines. The opportunity for indigenous peoples and local communities to apply their traditional ways of knowing, and interpret and act on information they understand are crucial components of cross-cultural environmental management regimes.

Circumpolar analysis of the Adélie Penguin reveals the importance of environmental variability in phenological mismatch.

Evidence of climate-change-driven shifts in plant and animal phenology have raised concerns that certain trophic interactions may be increasingly mismatched in time, resulting in declines in reproductive success. Given the constraints imposed by extreme seasonality at high latitudes and the rapid shifts in phenology seen in the Arctic, we would also expect Antarctic species to be highly vulnerable to climate-change-driven phenological mismatches with their environment. However, few studies have assessed the impacts of phenological change in Antarctica. Using the largest database of phytoplankton phenology, sea-ice phenology, and Adélie Penguin breeding phenology and breeding success assembled to date, we find that, while a temporal match between Penguin breeding phenology and optimal environmental conditions sets an upper limit on breeding success, only a weak relationship to the mean exists. Despite previous work suggesting that divergent trends in Adélie Penguin breeding phenology are apparent across the Antarctic continent, we find no such trends. Furthermore, we find no trend in the magnitude of phenological mismatch, suggesting that mismatch is driven by interannual variability in environmental conditions rather than climate-change-driven trends, as observed in other systems. We propose several criteria necessary for a species to experience a strong climate-change-driven phenological mismatch, of which several may be violated by this system.

Burrowing seabird effects on invertebrate communities in soil and litter are dominated by ecosystem engineering rather than nutrient addition.

Vertebrate consumers can be important drivers of the structure and functioning of ecosystems, including the soil and litter invertebrate communities that drive many ecosystem processes. Burrowing seabirds, as prevalent vertebrate consumers, have the potential to impact consumptive effects via adding marine nutrients to soil (i.e. resource subsidies) and non-consumptive effects via soil disturbance associated with excavating burrows (i.e. ecosystem engineering). However, the exact mechanisms by which they influence invertebrates are poorly understood. We examined how soil chemistry and plant and invertebrate communities changed across a gradient of seabird burrow density on two islands in northern New Zealand. Increasing seabird burrow density was associated with increased soil nutrient availability and changes in plant community structure and the abundance of nearly all the measured invertebrate groups. Increasing seabird densities had a negative effect on invertebrates that were strongly influenced by soil-surface litter, a positive effect on fungal-feeding invertebrates, and variable effects on invertebrate groups with diverse feeding strategies. Gastropoda and Araneae species richness and composition were also influenced by seabird activity. Generalized multilevel path analysis revealed that invertebrate responses were strongly driven by seabird engineering effects, via increased soil disturbance, reduced soil-surface litter, and changes in trophic interactions. Almost no significant effects of resource subsidies were detected. Our results show that seabirds, and in particular their non-consumptive effects, were significant drivers of invertebrate food web structure. Reductions in seabird populations, due to predation and human activity, may therefore have far-reaching consequences for the functioning of these ecosystems.

Sex-specific recruitment rates contribute to male-biased sex ratio in Adélie penguins.

Sex-related differences in vital rates that drive population change reflect the basic life history of a species. However, for visually monomorphic bird species, determining the effect of sex on demographics can be a challenge. In this study, we investigated the effect of sex on apparent survival, recruitment, and breeding propensity in the Adélie penguin (Pygoscelis adeliae), a monochromatic, slightly size dimorphic species with known age, known sex, and known breeding history data collected during 1996-2019 (n = 2127 birds) from three breeding colonies on Ross Island, Antarctica. Using a multistate capture-mark-recapture maximum-likelihood model, we estimated apparent survival (S^), recapture (resighting) probability (p^), and the probability of transitioning among breeding states and moving between colonies (ψ^; colony-specific non-juvenile pre-breeders, breeders, and non-breeders). Survival rate varied by breeding status and colony, but not sex, and pre-breeders had higher survival rates than breeders and non-breeders. Females had a higher probability of recruiting into the breeding population each year and may enter the breeding pool at younger ages. In contrast, both sexes had the same probability of breeding from year to year once they had recruited. Although we detected no direct sex effects on survival, the variation in recruitment probability and age-at-first reproduction, along with lower survival rates of breeders compared to pre-breeders, likely leads to shorter lifespans for females. This is supported by our findings of a male-biased mean adult sex ratio (ASR) of 1.4 males for every female (x^ proportion of males = 0.57, SD = 0.07) across all colonies and years in this metapopulation. Our study illustrates how important it can be to disentangle sex-related variation in population vital rates, particularly for species with complex life histories and demographic dynamics.

Survival differences and the effect of environmental instability on breeding dispersal in an Adelie penguin meta-population.

High survival and breeding philopatry was previously confirmed for the Adélie penguin (Pygoscelis adeliae) during a period of stable environmental conditions. However, movements of breeding adults as a result of an unplanned natural experiment within a four-colony meta-population provided interesting insights into this species' population dynamics. We used multistate mark-recapture models to investigate apparent survival and dispersal of breeding birds in the southwestern Ross Sea during 12 breeding seasons (1996-2007). The natural experiment was facilitated by the temporary grounding of two immense icebergs that (i) erected a veritable fence separating colonies and altering migration routes and (ii) added additional stress by trapping extensive sea ice in the region during 5 of 12 y. Colony size varied by orders of magnitude, allowing investigation of apparent survival and dispersal rates in relation to both environmental conditions and colony size within this meta-population. Apparent survival was lowest for the smallest colony (4,000 pairs) and similar for the medium (45,000 pairs) and large colonies (155,000 pairs), despite increased foraging effort expended by breeders at the largest colony. Dispersal of breeding birds was low (<1%), except during years of difficult environmental conditions when movements increased, especially away from the smallest colony (3.5%). Decreased apparent survival at the smallest colony could reflect differences in migration chronology and winter habitat use compared with the other colonies, or it may reflect increased permanent emigration to colonies outside this meta-population. Contrary to current thought, breeding penguins are not always philopatric. Rather, stressful conditions can significantly increase dispersal rates.

Potential for cascading impacts of environmental change and policy on indigenous culture.

Global environmental and societal changes threaten the cultures of indigenous peoples and local communities (IPLC). Despite the importance of IPLC worldviews and knowledge to sustaining human well-being and biodiversity, risks to these cultural resources are commonly neglected in environmental governance, in part because impacts can be indirect and therefore difficult to evaluate. Here, we investigate the connectivity of values associated with the relationship Ngatiwai (a New Zealand Maori tribe) have with their environment. We show that mapping the architecture of values-environment relationships enables assessment of how deep into culture the impacts of environmental change or policy can cascade. Our results detail how loss of access to key environmental elements could potentially have extensive direct and cascading impacts on the cultural values of Ngatiwai, including environmental responsibilities. Thus, considering only direct effects of environmental change or policy on cultural resources, or treating IPLC social-ecological relations simplistically, can severely underestimate threats to cultures.

Latitudinal, sex and inter-specific differences in mercury and other trace metal concentrations in Adélie and Emperor penguins in the Ross Sea, Antarctica.

We sought to determine mercury (Hg) and other trace metal concentrations in Adélie (Pygoscelis adeliae) and emperor penguin (Aptenodytes forsteri) breast feathers from the Ross Sea, Antarctica, and relate those concentrations to the trophic position and the habitats in which each of these species forage. Adélie penguin feathers from the southern Ross Sea colonies were higher in Hg than those sampled further north in the Ross Sea, potentially due to greater exposure to local sources, such as volcanism. Female Adélie penguins had lower feather total Hg concentrations than males. This may reflect female penguin's capacity to eliminate Hg through the egg development and laying process, or the larger and/or older prey items that male birds can consume, reflected by their higher trophic position. Emperor penguins have higher Hg concentrations than Adélie penguins which is also partially explained by Adélie penguins feeding at lower trophic levels than emperor penguins.

Trends in the breeding population of Adélie penguins in the Ross Sea, 1981-2012: a coincidence of climate and resource extraction effects.

Measurements of the size of Adélie penguin (Pygoscelis adeliae) colonies of the southern Ross Sea are among the longest biologic time series in the Antarctic. We present an assessment of recent annual variation and trends in abundance and growth rates of these colonies, adding to the published record not updated for more than two decades. High angle oblique aerial photographic surveys of colonies were acquired and penguins counted for the breeding seasons 1981-2012. In the last four years the numbers of Adélie penguins in the Ross and Beaufort Island colonies (southern Ross Sea metapopulation) reached their highest levels since aerial counts began in 1981. Results indicated that 855,625 pairs of Adélie penguins established breeding territories in the western Ross Sea, with just over a quarter (28%) of those in the southern portion, constituting a semi-isolated metapopulation (three colonies on Ross Island, one on nearby Beaufort Island). The southern population had a negative per capita growth rate of -0.019 during 1981-2000, followed by a positive per capita growth rate of 0.067 for 2001-2012. Colony growth rates for this metapopulation showed striking synchrony through time, indicating that large-scale factors influenced their annual growth. In contrast to the increased colony sizes in the southern population, the patterns of change among colonies of the northern Ross Sea were difficult to characterize. Trends were similar to southern colonies until the mid-1990s, after which the signal was lost owing to significantly reduced frequency of surveys. Both climate factors and recovery of whale populations likely played roles in the trends among southern colonies until 2000, after which depletion of another trophic competitor, the Antarctic toothfish (Dissostichus mawsoni), may explain the sharp increasing trend evident since then.

Climate change winners: receding ice fields facilitate colony expansion and altered dynamics in an Adélie penguin metapopulation.

There will be winners and losers as climate change alters the habitats of polar organisms. For an Adélie penguin (Pygoscelis adeliae) colony on Beaufort Island (Beaufort), part of a cluster of colonies in the southern Ross Sea, we report a recent population increase in response to increased nesting habitat as glaciers have receded. Emigration rates of birds banded as chicks on Beaufort to colonies on nearby Ross Island decreased after 2005 as available habitat on Beaufort increased, leading to altered dynamics of the metapopulation. Using aerial photography beginning in 1958 and modern satellite imagery, we measured change in area of available nesting habitat and population size of the Beaufort colony. Population size varied with available habitat, and both increased rapidly since the 1990s. In accord with glacial retreat, summer temperatures at nearby McMurdo Station increased by ~0.50 °C per decade since the mid-1980s. Although the Ross Sea is likely to be the last ocean with an intact ecosystem, the recent retreat of ice fields at Beaufort that resulted in increased breeding habitat exemplifies a process that has been underway in the Ross Sea during the entire Holocene. Furthermore, our results are in line with predictions that major ice shelves and glaciers will retreat rapidly elsewhere in the Antarctic, potentially leading to increased breeding habitat for Adélie penguins. Results further indicated that satellite imagery may be used to estimate large changes in Adélie penguin populations, facilitating our understanding of metapopulation dynamics and environmental factors that influence regional populations.