Use of Predator-Deterrent Fences to Increase Attwater's Prairie-Chicken Nest Success

We retrospectively evaluated 20 y of using predator-deterrent fences to mitigate unusually high nest predation for the critically endangered Attwater's prairie-chicken Tympanuchus cupido attwateri at the Attwater Prairie Chicken National Wildlife Refuge. Fences were constructed of 0.9-m high, 0.32-0.64-cm mesh hardware cloth, with 15.2-m long sides, and were staked at the bottom to discourage predators from going under the fence. Fences were placed around nests at = 3.2 d of incubation. Eighty-two percent of fenced nests were successful versus 12% for unfenced nests. Daily survival rate (DSR) increased from 0.9159 for unfenced nests in 1997-2011 to 0.9916 for fenced nests during 2000-2019. Fencing did not increase abandonment or reduce the proportion of eggs that hatched in successful nests. After 2012, we reduced fence sides from 15.2 m to 7.6 m in length. Larger and smaller fences were equally effective with respect to DSR and proportion of nests that were abandoned. The median proportion of eggs that hatched from successful nests was 6% higher for larger fences versus smaller fences, but this difference was not statistically significant. Predator-deterrent fences substantially increased Attwater's prairie-chicken nesting success in this study, and may represent a viable management strategy for increasing nesting success for other populations of ground-nesting birds with high conservation value.

A Method for Culturing Mussels Using In-River Cages

A variety of techniques have been used since the early 1900s to produce mussels for augmenting depleted populations, including the use of wire-covered crates to house fish bearing mussel larvae. Here we describe a modification of earlier techniques, which provides a viable, low-cost method for producing large numbers of mussels. Aluminum-framed cages covered with commercially available hardware cloth are used to confine glochidia-bearing fish. Juvenile mussels then excyst off the host fish, and fall to the substrate-covered cage bottom, which protects the mussels from predation until they mature into subadult mussels. To date, seven species of mussels totaling over 57,100 2- and 3-y-old mussels have been reared in these culture cages.

162 The Influence of Root Restriction on Flowering, Fruiting, Tree Growth, Yields, and Fruit Quality of Apple Trees

`Fuji'/MM.111, `Pink Lady'/M.7A, and `Summerfield'/M.7A apple trees were planted in several types of individual root restrictive bags in the field in 1995. Bags were made of Knit and Woven fabrics, Galvanize hardware cloth (6.4 cm) with various holes sizes and of different bag volumes. The bags confined the development of large roots to within the bag. Roots that penetrated the bag resulted in root branching and large root inhibition. As the roots enlarged, roots penetrating the bags were restricted in diameter by the fabric hole size. Roots enlarged to some degree on both sides of the fabric holes but were not killed by girdling within the first few years. Root restriction bags decreased trunk caliper, shoot growth, pruning weights, number of cuts per tree, increased flowering, fruit numbers, and weight per tree. Fruit firmness, soluble solids and color was increased and starch was lower than the nonbagged controls. In cage and tank trials pine and/or meadow voles easily penetrated all of the fabric and polypropylene bags within 24 h, except for the galvanized hardware cloth (6.4 cm). Susceptibility of each material to vole damage was tested by placement of an apple inside a small bag of each. Root restriction bags seemed to be a viable alternative to dwarfing rootstocks for control of tree size, early flowering, and early fruiting.

COMPARATIVE PERFORMANCE OF STANDARD AND MODIFIED PHEROMONE-BAITED WING TRAPS FOR CAPTURING HELIOTHIS ZEA (BODDIE)1 (LEPIDOPTERA: NOCTUIDAE)

The wing trap, although economical and commercially available, has never been seriously considered as a standard for monitoring populations of the corn earworm (CEW)/cotton bollworm, Heliothis zea (Boddie), mainly because it is considered inefficient relative to other available traps. Attempts were made to enhance the performance of the Pherocon 1C (P-1C) wing trap by modifying its structure and by varying the placement of the pheromone within the trap. P-1C traps receiving 40–50 g of supplemental adhesive captured 5.1-fold more CEW males than did the P-1C standard. The introduction of horizontal barriers of either Lexan or hardware cloth across the center of the P-1C trap or the placement of Lexan strips to close side trap openings had no effect on the number of CEW males captured. Traps with the pheromone located 1.0–1.5 cm from the top center of the trap captured more males than did traps with the pheromone placed an equivalent distance from the bottom of the trap. Centering the pheromone approximately 2.5 cm back from the end opening of the trap also increased the number of CEW males captured over that of traps in which the pheromone was placed at the top center of the trap. Data suggest that parameters influencing the efficiency of P-1C traps for capturing male CEW are poorly understood.