Population Size Patterns Research Articles

Analysis of Changing Pattern of Population at Haldia Municipal Area, West Bengal

Urban growth of Haldia Town within the last 40 years is observed through census data and Municipality map of different times which points out the dramatic change in the study area. Census data and Municipality map have been used to analyse the population growth and areal extension. Findings reveal that Haldia Municipality has experienced rapid change in patterns of population size and population density. In order to achieve ecological sustainability and human wellbeing, proper urban planning mechanisms should be in place.

Reconstruction and prediction of invasive mongoose population dynamics from history of introduction and management: aBayesian state‐space modelling approach

Summary An understanding of the underlying processes and comprehensive history of invasive species is necessary to assess the long‐term effectiveness of invasive species management. However, continuous, long‐term labour‐intensive population surveys on invasive species are often not feasible. Thus, it is important to learn about their dynamics through management action and its consequences. Amami Island, Japan, has an ongoing large‐scale and long‐term eradication programme of invasive small Indian mongooses. To estimate the long‐term pattern of population size and the parameters determining the dynamics, including anthropogenic removal, we applied a surplus‐production model within a Bayesian state‐space formulation incorporating the initial population size, number of captures and capture effort. Using the estimated process model directly, we conducted stochastic simulations to evaluate the feasibility of eradication. Estimated 32‐year annual capture probability of mongooses has increased since their introduction. The population size started to decline in 2001; mean population size in 2000 was 6141 (95%CI: 5415–6817), and declined to 169 (95%CI: 42–408) by 2011. Parameter estimates of a Weibull catchability model indicated that there was large individual heterogeneity in the probability of being captured, and per‐effort capture probability declined with an increase in annual capture effort. The simulation study indicated that the eradication feasibility in 2023 would be over 90% if the same annual capture effort is upheld as in 2010 (2 075 760 corrected trap‐days). However, increasing annual capture effort would have little effect on shortening the time to eradication. Synthesis and applications. A hierarchical model that incorporates multiple types of data to reveal long‐term population dynamics has the potential to be updated with the outcomes of control efforts, and will enhance adaptive management of invasive species. This approach will offer valuable information about trade‐offs between time to eradication success and effort per unit time in a long‐term eradication project, and the length of time needed to continue management actions to achieve eradication success.

Environmental niche of the smut lizard population on a sandy coastal ecosystem of Southeastern Tenerife (Canary Islands)

AbstractRelationships among environmental patterns and population size of the smut lizard Gallotia galloti galloti Oudart, 1839 (Sauria Lacertidae) were examined in the context of longer time‐scale variability on a sandy beach and adjacent environments of Southeastern Tenerife. Seasonal and yearly patterns in the population size were likewise analyzed in relation to climatic and anthropic variables. Six sampling plots (coastal, sweet tabaiba, tuff, lava, sandy lava and crater) were selected following a perpendicular transect to the sandy fringe that extends from the beach toward the volcanic interior. Pitfall trapping was conducted from 1984 to 2005, and capture–mark–recapture technique and the Jolly–Seber method were used to estimate population sizes. The highest population size estimates were shown on the sandy lava plot and the neighboring lava plot, reaching values of about 3500 individuals ha−1 during the spring. The population was active almost the whole year, with seasonal patterns of activity from March to October. Seasonal temperature and population size patterns were correlated but the ‘calima’ episodes produced some disturbance. Gallotia galloti galloti was one of the most abundant lizards of all the species studied and its population size has not remained stable over the study period, probably because of the absence of predation and competition, and because of human interference and environmental instability.