Age‐related changes in diet have implications for competitive interactions and for predator–prey dynamics, affecting individuals and groups at different life stages. To quantify patterns of variation and ontogenetic change in the diets of Tasmanian devils
Sarcophilus harrisii
, a threatened marsupial carnivore, we analyzed variation in the stable isotope composition of whisker tissue samples taken from 91 individual devils from Wilmot, Tasmania from December 2014 to February 2017. Both δ
13
C and δ
15
N decreased with increasing age in weaned Tasmanian devils, indicating that as they age devils rely less on small mammals and birds, and more on large herbivores. Devils <12 months old had broader group isotopic niches, as estimated by Bayesian standard ellipses (SEA
B
mode = 1.042) than devils from 12 to 23 months old (mode = 0.541) and devils ≥24 months old (mode = 0.532). Devils <24 months old had broader individual isotopic niches (SEA
B
mode range 0.492–1.083) than devils ≥24 months old (mode range 0.092–0.240). A decrease in δ
15
N from the older whisker sections to the more recently grown sections in devils <24 months old likely reflects the period of weaning in this species, as this pattern was not observed in devils ≥24 months old. Our data reveal changes in the isotopic composition of devil whiskers with increasing age, accompanied by a reduction in isotopic variation both among population age classes and within individuals, reflecting the effect of weaning in early life, and a likely shift from an initially diverse diet of small mammals, birds, and invertebrates towards increasing consumption of larger herbivores in adulthood.
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Coleophora deauratella (red-clover casebearer moth, RCCB) was first confirmed as present in New Zealand during late 2016. It devastated red-clover seed crops throughout the mid-Canterbury region during the 2016/17 growing season but its distribution and control options were unknown. Therefore, traps containing a male pheromone specific to RCCB were located inside either red-clover seed crops or hay crops at 27 sites throughout the South Island and lower North Island during summer 2017/18. Moth numbers were monitored at 7-14 day intervals between November and February. RCCB was confirmed as present at all 27 sites (from Invercargill to Masterton). Peak flights occurred during December with mean moth catch well correlated in thermal time, with half of adult emergence occurring 285°C days from 1 July (baseline temperature=12°C). Laboratory-based trials were conducted against live moths to evaluate the effectiveness of various organophosphate and synthetic pyrethroid insecticides. Tau-fluvalinate, lambda cyhalothrin and chlorpyrifos each provided >90% control of moths so chemical control is possible, if required. However, an integrated pest-management control strategy needs to be tested and evaluated.
Good pasture management requires an accurate knowledge of whole-farm feedbase, yet most systems for measuring pasture growth are manually operated and time consuming. A newly developed pasture-measuring device enables remote measurement of pasture height on a regular basis. This study investigated the accuracy of such a device compared with a rising plate meter, then assessed the device on a pure perennial ryegrass paddock at a research farm, followed by field testing in a perennial ryegrass/white clover paddock on a commercial dairy farm. A strong correlation (R2 = 0.93) was obtained between collected DM yield and device-derived pasture height within the pure perennial ryegrass paddock but the correlation was weaker (R2 =0.68) with data from the dairy farm perennial ryegrass/white clover paddock. There is considerable potential to improve upon these initial data through the use of adjusted calibrations. Findings demonstrate the device has the potential to accurately estimate pasture growth.
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