Annual Population Growth Rate Research Articles

Modeling the life cycle of the spotted lanternfly (Lycorma delicatula) with management implications

The spotted lanternfly (SLF) is an invasive pest that emerged in the US less than a decade ago. With few natural enemies and an ability to feed on a wide variety of readily available plants the population has grown rapidly. It is causing damage to a wide range of natural and economically important farmed plants and at present there is no known way to stop the growth and spread of the population. However, a number of control measures have been proposed to limit the growth and the effectiveness of some of these have been assessed via empirical studies. Studies to estimate the natural mortality rate of the lanternfly’s different life stages and other properties of its life cycle are also available. However, no attempt to integrate this empirical information to estimate population level characteristics such as the population growth rate and the potential effects of proposed control measures can be found in the literature. Here, we introduce a simple population dynamics model parameterized using available information in the literature to obtain estimates of this type. Our model suggests that the annual growth rate of the SLF population in the US is 5.47, that only three out of six proposed control measures considered here have the potential to decrease the population even if we can find and treat each SLF in every stage, and that even with a combined strategy involving the most effective proposed control measures about 35% of all SLF in the relevant stages must be found and treated to turn the current population growth into decline. Suggesting that eradication of the spotted lanternfly over larger geographical areas in the US will be challenging, and we believe that the modeling framework presented here may be useful in providing estimates to inform feasibility assessment of proposed management efforts.

Population-level effects of polychlorinated biphenyl (PCB) exposure on highly vulnerable Indo-Pacific humpback dolphins from their largest habitat

While polychlorinated biphenyl (PCB)-related risks have been reported at the cellular, organ, and individual levels in some marine mammals, studies quantifying the PCB-associated population-level effects are limited. Here, we combined chemical analysis and individual-based model simulation to investigate the impact of PCBs on the Indo-Pacific humpback dolphin (sub)population from the Pearl River Estuary (PRE). An annual PCB accumulation rate of 0.29 ± 0.07 mg/kg lipid per year was estimated based on the measured age-specific male data as males continue to accumulate PCBs throughout their lifetime, without depurating contaminant loads. Using the Taiwan Strait dolphin population with low PCBs as a baseline, we compare our model simulations in PRE population to estimate relative population impacts of PCBs and other stressors. When using the current vital rates of the PRE dolphins which have been affected by PCBs and other stressors (e.g., underwater noise, prey limitation, etc.), our simulations revealed a substantial decline (8.1%) in the annual population growth rate (λ) of PRE metapopulation compared to baseline over the next 100 years. At the estimated PCB accumulation rate, the PCB-mediated effects on calf survival and immunity would cause a slight decline (0.9%) in λ relative to baseline. Our findings suggest a relatively limited impact of PCBs on the long-term survival of PRE dolphins among all stressors. However, it should be noted that even under model simulations where dietary PCBs were eliminated, humpback dolphins would still need a long time to reduce their PCB burdens to a relatively “safe” level through biological cycling. Considering that the baseline vital rates might also have been affected by PCBs and other stressors, our results are considered relative rather than absolute. This study provides a starting point for quantifying population-level consequences of contaminant exposure on humpback dolphins, although more efforts are needed to perfect this type of analysis.

Estimates of regional annual abundance and population growth rates of white sharks off central California

Determining population trends is critical for evaluating management actions and prioritizing species protections. In this study, we used empirical data to produce an estimate of the population trend for sub-adult and adult white sharks in central California. We used the unique dorsal fin morphology to build a mark-recapture data set in a modified Jolly-Seber model (POPAN formulation) to estimate annual abundance and then investigate population growth rates using parametric bootstrapping methods for sub-adult and adult sharks (males and females). For all demographic groups combined, we found equivocal evidence for a positive regional population growth (λ = 1.07 (95% CI = 0.91 to 1.23)). However, sex- and size-specific population growth rate estimates provided some evidence of population increases for reproductively mature males (λ = 1.06 (95% CI = 0.99 to 1.13)) and females (λ = 1.06 (95% CI = 0.95 to 1.17)). For sub-adult male and female white sharks, point estimates of λ were positive but uncertainty prevents strong inference (λ = 1.07 (95% CI = 0.85 to 1.29)) and (λ = 1.08 (95% CI = 0.88 to 1.28)), respectively. Our findings of a potential increase in reproductive-aged white sharks in central California may be a result of regional fluxes in density or attributed in part to current protection efforts and subsequent increase in abundance of pinnipeds as well as reduced gill-net fisheries mortality of juveniles. A trend estimate for the entire northeastern Pacific will require obtaining similar data across known aggregation areas along the west coast of North America.

A CONFIRMATORY ANALYSIS OF FOOD SECURITY IN NORTH SUMATERA

This study aims to provide empirical evidence and investigations on the development of food security in North Sumatera Province (PSU). This research was conducted in districts/cities in North Sumatera Province. Data collection techniques in this study were secondary data collection (aspects of food production per year in a cycle of two harvests calculated on an average, annual population growth rate and annual rice field area), observation and interviews. The analysis technique using Confirmatory Factor Analysis. The results showed that the trend of food security in the aspect of food production, in the aspect of production value, has generally decreased, so that the fulfillment of food production is only eighty percent and shortages each year are met through imports from other countries. Welfare in the PSU is determined by confirmatory factors with the availability of agricultural land, then population and food security. Keywords: confirmatory analysis, food security, north sumatera, agriculture, starving

Next-generation sequencing of the soil nematode community enables the sustainability of banana plantations to be monitored

Uganda faces a considerable challenge to match its food production to an annual population growth rate of 3%. Cooking bananas are the country's most produced staple crop but the annual national harvest is not increasing. The crop grows on infertile soils that are normally fertilised organically and often susceptible to erosion. Soil nematodes are well-established as bioindicators of soil quality that can support environmental monitoring and assessment of the sustainability of agricultural systems. These invertebrates are a highly ranked indicator of biodiversity with molecular approaches available. Consequently, we have applied next-generation DNA sequencing of soil nematodes to evaluate soil quality of Ugandan banana plantations. The aim is to establish a method for constructing an aspect of an environmental biosafety dossier with the future aim of assessing the impact of transgenic crops and improving current cropping systems. The soil samples did not differ significantly in any of the measured soil chemistry factors, soil texture or percentage of organic matter. Thirty taxons of soil nematodes other than the plant parasites were recovered from soil supporting nine banana plantations plus three each from coffee and banana-coffee interplants from East and West Uganda. Cluster analysis correctly allocated each plantation to the crop/intercrop being grown when based on the abundance of taxa rather than taxa presence or absence. This indicates that the host has considerable effects on the abundance of specific nematode species within the soil. Overall, nematodes were more abundant in soil from coffee plantations than from banana-coffee interplants with the lowest values being from fields supporting just banana. Only the basal and trophic diversity indices and the percentage of nematodes that are rapid colonisers varied between the three plantation types. The soil of all fifteen plantations can be classified as having a mature soil web condition with low physical disturbance, limited chemical stressors, moderately high nutrient enrichment and balanced decomposition channels.

Recent Dynamics and Trends of Landbird Populations on Saipan, Northern Mariana Islands

The avifauna of Saipan, Northern Marianas Islands, includes a variety of endemic and range-restricted species of conservation concern. Monitoring population dynamics, trends, and vital rates of these species can help inform their conservation. Here we apply reverse symmetry models to 11 years (2008–2018) of capture–recapture data from 6 mist-netting stations on Saipan to estimate adult apparent survival probabilities, recruitment rates, population growth rate, and demographic contributions to population growth rate for five bird species: Mariana Kingfisher (Todiramphus albicilla albicilla), Rufous Fantail (Rhipidura rufifrons saipanensis), Bridled White-eye (Zosterops conspicillatus saypani), Golden White-eye (Cleptornis marchei), and Micronesian Myzomela (Myzomela rubratra saffordi). Population growth rate estimates suggested declines for all species except Golden White-eye. Survival was the largest contributor to annual population growth rate for all species except Micronesian Myzomela, for which population change was largely determined by recruitment (including 1-yo recruits and immigrating adults). Hierarchical models applied to the two species with the most captures and recaptures, Rufous Fantail and Golden White-eye, showed greater temporal than spatial variation in vital rates. Annual variation in vital rates confirmed the importance of survival in explaining population change, but also showed recruitment to be especially important in driving population growth in years of population increase. Our results provide new insights into drivers of population change in these species and highlight information gaps, such as a need for understanding seasonal habitat use and the scale and timing of movements.

Assessment of Grey Water Generation and Characteristics to Reduce Clean Water Resources Usage in Pekanbaru City

Pekanbaru city development in various sectors is growing rapidly in line with the population growth. The average annual population growth rate (2017-2020) is 2,64%. The consumption of clean water for each person is influenced by various factors such as: climate, population characteristics, socio-economy, and variety of activities. The volume of grey water (non-toilet liquid waste) generated ranges from 50% -80% of the total clean water used. The characteristics of grey water depend on the diversity of household uses of clean water. This study aims to assess the generation and characteristics of grey water in the city of Pekanbaru. Furthermore, it can be seen that critical flows that have the potential to be reused, such as for watering plants and rinsing / flushing toilets, will reduce the use of clean water sources. The method used is data collection (secondary and primary) and literature studies, assessing the characteristics of grey water by referring to the quality standards of domestic wastewater PERMEN LHK RI No. 68/2016, and conducted a system assessment using MFA-STAN. The grey water survey and sampling were carried out in six densely populated sub-districts (Tampan, Tenayan Raya, Marpoyan Damai, Bukitraya, Rumbai Pesisir, and Limapuluh). The results obtained, the generation of grey water in Pekanbaru city is 57,869,008.51 m3 / year. The characteristics of the grey water in Pekanbaru City (average value) are pH 7.42; BOD 44,21 mg / L; COD 118.99 mg / L; TSS 17 mg / L; Oil and Fat 6.67 mg / L; and Ammonia 6.09 mg / L. Grey water has the potential to be reused for sanitation sector and agricultural sector so that it can reduce the use of clean water by up to 50%.

MatthewYglesiasOne Billion Americans: The Case for Thinking Bigger. Portfolio, 2020. 288 p. $28.00

MatthewYglesiasOne Billion Americans: The Case for Thinking Bigger. Portfolio, 2020. 288 p. $28.00

The Characteristics, Influencing Factors, and Push-Pull Mechanism of Shrinking Counties: A Case Study of Shandong Province, China

To analyze the characteristics, influencing factors, and microscopic mechanisms of county-level city shrinkage, this paper uses a quantitative push-pull model to explore the shrinking counties of Shandong Province between 2000 and 2018. The measurement method formulates three research objectives. First, the shrinking intensity and characteristics are analyzed according to statistics about the average annual rate of population growth, the primary production proportion, and public expenditure. Second, the influence factors are explored. Living standards, industrial development, social input, and public resource indicators are selected to quantitatively identify the push factors and pull factors and the correlated relationship of how the factors influence the population decline using ridge regression. Finally, the circular feedback mechanism and push-pull effect of multiple factors are explained. How do the factors affect each other and which is the decisive factor shaping county shrinkage? The push-pull mechanism is analyzed using dynamic relationship testing and the Granger causality test. The results show that the shrinkage of county-level cities faces common problems, including lack of resources, slowing down of the economy, and declining cityscape quality of life, which are the push factors for the population decline. There are differentiated characteristics of shrinkage. There has not yet been a full-scale recession in Shandong Province in terms of the degree of shrinkage. The towns with population loss accounted for only 15.4%, and the loss of population was less than 10% in ten years. In terms of impact mechanisms, county economic strength has a nonlinear correlation to population migration. Some counties tend to shrink in population and society. The degradation of the cultural environment, quality of life, and social welfare highlight social shrinkage signs in counties. A healthy living environment, equal public services, and a slowing down of relative deprivation have become essential pull factors for migration. County governments should shift from economic growth to people’s well-being, balancing government governance, economic growth, cultural development, environmental protection, and improving the livability level, as they are important directions for improving shrinking counties’ resilience.

2021 Analysis of Elderly people living in Briddha Ashram

Ageing is a natural phenomenon and an inevitable process. Population ageing is pervasive since it is creating humanitarian, social and economic problems in many countries of the world including Nepal. Nepalese society is in a phase of modernization. There is modification in the cultural norms and traditional family support systems for elderly in Nepal which have placed substantial strain in caring elderly people. In Nepal, there were 1.5 million in 2001 and 2.1 million in 2011, elderly inhabitants, which constitute 6.5 percent and 8.1 % of the total population in the country. During the years 1991-2001, the annual elderly population growth rate was 3.39 percent, higher than the annual population growth rate of 2.3 percent. Growing numbers of elderly people are suffering problems in different aspect, but there are limited studies in relation to general morbidities as well as specific in this group of people. The government of Nepal has formulated a National policy, act and regulations on ageing and the problems of elderly; however, this has not been operationalised because of limited resources. In this background of problems that elderly people are facing and government slow initiatives, this paper is illustrated with the objective to explore the different dimensions of ageing and health and health related services for aging people in Nepal using different information for the purpose of further concrete steps in the benefits for elders.

Breeding population trends and recent changes in the nesting behaviour of the White Stork Ciconia ciconia L., 1758 in Navarre, north of Spain

The white stork Ciconia ciconia is one of the most emblematic birds in rural habitats of Europe. Its populations showed a drastic decline during the 20th century, followed by a rapid recovery in the last decades. The population increase has led to a relaxation in the specie’s monitoring effort, the last Spanish national official census having been conducted more than 15 years ago. In order to update this knowledge, this study shows the results of a breeding population census conducted in Navarre during the spring of 2018, describing the preferences in nest location, and comparing the current breeding population size with that described in the literature published since 1960. Our results show a breeding population of 739 pairs, which is the highest value ever recorded. However, this increase in the number of pairs has not been associated with a significant expansion of the specie’s distribution area, which is still limited to the southern half of Navarre. The only relevant colonisation would be the 5 pairs established in the Pamplona district. Most pairs (86.3%) nested in colonies, with an average size of 9.2 nests. Most of the nests were located in trees (49.0%), followed by buildings (28.8%), cut trees (10.0%), pylons (6.9%) and other types of structures (antennas, chimneys, artificial nests, cranes..., 5.3%). A comparison of the current situation with previous censuses shows that there has been an annual population growth rate of 6.6%, with an important change in nesting habits, both in the percentage of pairs that nest in colonies and in the substrate selected to build the nest. The possible causes that could explain these changes and the conservation implications for the species are discussed.

Population responses to observed climate variability across multiple organismal groups

A major challenge in ecology is to understand how populations are affected by increased climate variability. Here, we assessed the effects of observed climate variability on different organismal groups (amphibians, insects, mammals, herbaceous plants and reptiles) by estimating the extent to which interannual variation in the annual population growth rates (CVλ) and the absolute value of the long‐term population growth rate (|log λ|) were associated with short‐term climate variability. We used empirical data (≥ 20 consecutive years of annual abundances) from 59 wild populations in the Northern Hemisphere, and quantified variabilities in population growth rates and climatic conditions (temperature and precipitation in active and inactive seasons) calculated over four‐ and eight‐year sliding time windows. We observed a positive relationship between the variability of growth rate (CVλ) and the variability of temperature in the active season at the shorter timescale only. Moreover, |log λ| was positively associated with the variability of precipitation in the inactive season at both timescales. Otherwise, the direction of the relationships between population dynamics and climate variability (if any) depended largely on the season and organismal group in question. Both CVλ and |log λ| correlated negatively with species' lifespan, indicating general differences in population dynamics between short‐lived and long‐lived species that were not related to climate variability. Our results suggest that although temporal variation in population growth rates and the magnitude of long‐term population growth rates are partially associated with short‐term interannual climate variability, demographic responses to climate fluctuations might still be population‐specific rather than specific to given organismal groups, and driven by other factors than the observed climate variability.

Reconstruction of brown bear population dynamics in Slovenia in the period 1998-2019: a new approach combining genetics and long-term mortality data

Reliable data and methods for assessing changes in wildlife population size over time are necessary for management and conservation. For most species, assessing abundance is an expensive and labor-intensive task that is not affordable on a frequent basis. We present a novel approach to reconstructing brown bear population dynamics in Slovenia in the period 1998-2019, based on the combination of two CMR non-invasive genetic estimates (in 2007 and 2015) and long-term mortality records, to show how the latter can help the study of population dynamics in combination with point-in-time estimates. The spring (i.e. including newborn cubs) population size estimate was 383 (CI: 336-432) bears in 1998 and 971 (CI: 825-1161) bears in 2019. In this period, the average annual population growth rate was 4.5 %. The predicted population size differed by just 7 % from the non-invasive genetic size estimate after eight years, suggesting that the method is reliable. It can predict the evolution of the population size under different management scenarios and provide information on key parameters, e.g. background mortality and the sex- and age-structure of the population. Our approach can be used for several other wildlife species, but it requires reliable mortality data over time.

Demographic analysis reveals a population decline of the Longnose stingray Hypanus guttatus in Northeastern Brazil

High fishing pressure on elasmobranchs had caused declines in their populations worldwide, though these declines may not always be observed due to lack of monitoring. The Longnose stingray Hypanus guttatus is one of the most abundant and captured species in Northeast Brazil, mainly as bycatch by shrimp trawl. We aimed to estimate how the population of H. guttatus behaves in the face of different fishing pressures in the Northeast. For this purpose, we used a life matrix analysis from the metadata of three studies in the Northeast of Brazil (Bahia, Alagoas and Rio Grande do Norte). The average annual population growth rate estimated for the three states was strongly negative (−11.83%). However, there was considerable regional variation: data from Bahia showed in fact a low level of positive growth (3.24%) compared to the severe population decline (−29.47% per year) in Rio Grande do Norte, caused by the high mortality from shrimp trawling We conclude that the Longnose stingray has a high risk of long-term population decline in Northeastern Brazil, mainly caused by the high capture rate of juveniles.

Concerning demographic limitations on the population growth rate of West Australian (Breeding Stock D) humpback whales

The upper bound of 0.126 on the maximum demographically possible annual growth rate for humpback whales that has standardly been imposedon recent applications of age-aggregated assessment models for this species in the IWC Scientific Committee, is based on an analysis that assumessteady age structure. It is conceivable that transient age-structure effects could admit greater population growth rates for short periods than suggestedby such a bound. This possibility is addressed by developing an age-structured population model in which possible density dependent changes inpregnancy rate, age at first parturition and natural mortality are modelled explicitly, and allowance is made for the possibility of natural mortalityincreasing at older ages. The model is applied to the case of the west Australian humpback whale population (Breeding Stock D), for which breedingground surveys over the 1982–1994 period provide a point estimate of 0.10 for the annual population growth rate. Results based upon the breedingpopulation survey estimate of abundance of 10,032 in 1999 suggest that 0.12 is the maximum demographically feasible annual rate of increase forthis stock over 1982–1994 if it is a closed population. This result is based on essentially the same parameter choices as led to the earlier r = 0.126bound, i.e. that in the limit of low population size the age at first parturition approaches five years from above, the annual pregnancy rate 0.5 frombelow, and the annual natural mortality rate 0.01 from above. Transient effects do not appear able to reconcile the observed rate of increase withless extreme values of demographic parameters than led to the previously imposed upper bound of 0.126 on the maximum possible annual growthrate. Although use of extreme values reported for demographic parameters for Northern Hemisphere humpback whale populations, rather than thoseconsidered here, would reduce this suggested maximum rate of 0.12, the conclusion that transient effects have a very limited impact on observedpopulation growth rates would be unlikely to change.

A drop in immigration results in the extinction of a local woodchat shrike population

AbstractThe demographic reasons of local population extinctions are rarely known which hampers learning for preventing extinction of other populations. Here we study the demography of a population of the endangered woodchat shrike Lanius senator at the edge of its distribution range from 1966 to 1992. We recorded the number of breeding pairs and collected reproduction and capture‐recapture data which were analysed with an integrated population model. Population size and most demographic rates fluctuated, but did not show long‐term trends. The most important demographic driver for the variation in the annual population growth rate was immigration. Despite its dependence on immigration, the local population was not necessarily a sink but may have been part of a balanced dispersal system. A population viability analysis showed that the risk was zero for the population to go extinct due to stochastic events during the 10 years after 1992. Yet, the population went extinct 6 years after the end of the study. The only demographic mechanism that can explain the fast extinction is a stop of immigration. The population was always dependent on immigration due to the strong dispersal of the shrikes and became more isolated due to the overall decline of the species. Our results suggest that the reservoir of potential immigrants may have become insufficient to maintain the local population and highlights that local populations can go extinct without the need of local changes in demography. Successful conservation of bird populations with similar demography as woodchat shrikes need to focus on spatial scales that extend significantly beyond the local one.

Analysis of unsignalized intersection upgrading at constrained area in the city of Banda Aceh

The city of Banda Aceh is the capital city of Aceh province. The city’s population is 259,913, and the city’s annual population growth rate is 1.97% (BPS, 2018). Punge intersection is one of the intersections in Banda Aceh; this intersection is passed by the numerous and dense traffic. Based on the observation in certain hours at Punge intersection, it reveals several problems, namely: the intersection capacity and the performance level of the intersection. As a result, this study is aimed to evaluate the performance of Punge intersection. The intersection calculation was based on the Indonesia Highway Capacity Manual (MKJI, 1997). The benefit that can be obtained from this research is to eliminate traffic conflict. According to the survey, it was discovered that the dominant traffic (3,053 pcu/hours) was at the Sultan Iskandar Muda Street, D, from the central city to Ulee Lheu; on the contrary, only a few traffic (559 pcu/hours) passed on Cempaka Punge Jurong Street, A. By way of conclusion, the intersection capacity is inadequate because the degree of saturation has exceeded 0.85, viz 1.851. Therefore, Simpang Punge needs some improvements, such as repairing traffic lights and its geometric.

Determining Optimal Stock Density of Punjab Urial (Ovis vignei punjabiensis) in Captivity for Breeding, Population Growth and Reintroduction Potential.

The Punjab urial (Ovis vignei punjabiensis) is an endangered wild sheep of Pakistan, raised in captivity with the aim of re-introduction. To date, no information is available about population trends of this species in captivity. The current study was conducted with the aim to evaluate the population trend to better guide captive breeding for improved productivity and conservation value. Annual population data recorded and maintained by the Wildlife Department Khyber Pakhtunkhwa, Pakistan, were used. The data were compiled and analyzed in Microsoft Excel 2010 for determining growth rates and package Growthcurver in R-version 3.5.1 was used to produce a graphical representation of the population trend. The overall average annual population growth rate was rN = 0.22. Results revealed a fast initial growth rate with an average value of rN = 0.4 per year. Birth rates of bN = 0.45 for the first nine years were considerably higher than the death rates dN = 0.22 and the population increased with exponential growth. In the subsequent year, very high mortalities rates (dN = 1.2), likely attributed to the clumping of the population, resulted in the collapse of the population, leaving it in a state of unstable equilibrium. Results support the evaluation of management data to reveal carrying capacity in captive populations, to guide and inform appropriate release of surplus animals into natural habitats.

Is Lahore's urban system ready to sustain climate change? The case in Pakistan

Lahore, the second largest city of Pakistan and home to more than 12 million people with annual population growth rate of 2.4%, has experienced deadly smog duration since last three years. Climate Change is a global challenge and administrations in major cities around the globe have started addressing the issue on top level. Lahore has also seen establishment and operation of various public sector institutions/offices which explicitly or implicitly claim to help Lahore sustain changing needs of urban system due to climate change. However, little is documented yet whether how effective have these interventions been at institutional level. This paper investigates policies, plans, procedures and regulations (whichever available) for seven relevant government offices on the basis of five key assessment areas to explore whether Lahore’s urban system is ready to sustain the challenge of Climate Change. The investigation covers the debate on policy to the plan level. Institutional abilities of selected government offices have been analyzed to ascertain their efficacy. In essence; the capacity of current system has been documented, the gaps in the system have been outlined and the prospective solutions for the way forward have been suggested in this study.

Changes in age-structure over four decades were a key determinant of population growth rate in a long-lived mammal.

A changing environment directly influences birth and mortality rates, and thus population growth rates. However, population growth rates in the short term are also influenced by population age-structure. Despite its importance, the contribution of age-structure to population growth rates has rarely been explored empirically in wildlife populations with long-term demographic data. Here we assessed how changes in age-structure influenced short-term population dynamics in a semi-captive population of Asian elephants Elephas maximus. We addressed this question using a demographic dataset of female Asian elephants from timber camps in Myanmar spanning 45years (1970-2014). First, we explored temporal variation in age-structure. Then, using annual matrix population models, we used a retrospective approach to assess the contributions of age-structure and vital rates to short-term population growth rates with respect to the average environment. Age-structure was highly variable over the study period, with large proportions of juveniles in the years 1970 and 1985, and made a substantial contribution to annual population growth rate deviations. High adult birth rates between 1970 and 1980 would have resulted in large positive population growth rates, but these were prevented by a low proportion of reproductive-aged females. We highlight that an understanding of both age-specific vital rates and age-structure is needed to assess short-term population dynamics. Furthermore, this example from a human-managed system suggests that the importance of age-structure may be accentuated in populations experiencing human disturbance where age-structure is unstable, such as those in captivity or for endangered species. Ultimately, changes to the environment drive population dynamics by influencing birth and mortality rates, but understanding demographic structure is crucial for assessing population growth.