detectability

Management of invasive mammal pests plays an integral role in the conservation of New Zealand’s native flora and fauna. Models fitted to pest capture data can guide conservation managers by providing estimates of pest densities within a management area, or probabilities of absence for declaring local eradication. A key parameter of these models is the detectability, i.e. the probability of an animal being detected by a surveillance device for a given amount of survey effort.

Urbanisation is a significant and increasing threat to biodiversity at the global scale. To maintain and restore urban biodiversity, local communities and organisations need information about how to modify green spaces to enhance species populations. ‘Citizen science’ initiatives monitoring the success of restoration activities also require simple and robust tools to collect meaningful data. Using an urban monitoring study of the bellbird (Anthornis melanura), we offer advice and guidance on best practice for such monitoring schemes.

Factors influencing detection probability in line transect distance sampling were investigated to estimate the abundance of four common farmland birds on 12 sheep & beef farms in the South Island of New Zealand. Our primary aim was to evaluate the necessity of employing distance methods to correct for heterogeneity in detection probability.

We evaluated the accuracy and precision of three population estimation methods (mark–resight, distance sampling and five-minute bird counts) for two populations of South Island robin (Petroica australis australis) of known size in the Eglinton Valley, Fiordland, over 5 years (March and August, 2005–2009). The performance of these population estimators was compared to known robin abundance derived from simultaneous territory mapping of individually marked birds.

Growing concerns about significant biodiversity decline due to agricultural intensification are increasingly leading consumers to seek agricultural products that are produced sustainably. To raise awareness of sustainable land management and direct policy and research to mitigate adverse impacts, large-scale bird monitoring programmes are being used in Europe. New Zealand’s first farmland bird monitoring scheme was established in 2004 to quantify bird abundance on 98 farms across three sectors (sheep & beef, dairy and kiwifruit).

Robust monitoring systems are required to improve the ecological outcomes of management actions aimed at preventing biodiversity loss. We present a pilot study that measured assemblages of widespread and common bird species at the national scale in New Zealand. Bird surveys were undertaken at 18 sampling locations (six per land cover class: forest, shrubland and non-woody) randomly selected from a national grid. The full sampling protocol (five count stations surveyed on each of two consecutive days) was implemented at 80% of sampling locations.