Natural mortality of juvenile rabbits (Oryctolagus cuniculus ) in North Canterbury, New Zealand

1993 ◽  
Vol 20 (6) ◽  
pp. 815 ◽  
Author(s):  
DL Robson
Keyword(s):  
New Zealand ◽  
Soil Type ◽  
Oryctolagus Cuniculus ◽  
Early Summer ◽  
Late Spring ◽  
Natural Mortality ◽  
Marked Influence ◽  
Breeding Activity ◽  
Pasture Quality

Rabbit-breeding stops were monitored over 35ha of improved farmland, with relatively stable rabbit numbers, in North Canterbury, New Zealand. The number of stops dug varied seasonally, with most in spring, fewest in autumn. Pasture quality appeared to have a marked influence on breeding activity and productivity of the rabbits. Of the 427 breeding stops located, litters were found in 33%. Most (97%) of these stops were lined with grass and belly fur from the doe. Most juvenile rabbit mortality occurred prior to weaning. Of the 126 litters monitored, 38% were preyed upon, 29% drowned and 20% were either preyed upon or drowned prior to emergence. Young drowned when sufficient rainfall for a particular soil type caused flooding of stops. In all, 13% of litters were weaned and left the breeding stop, with late spring-early summer being the most favourable period for survival. Predator numbers were lowest during this period. Ferrets were the most numerous predator; cats and harriers were also present. Disease was not significant. Of those rabbits that emerged, approximately 50% survived to 14 weeks of age. Less-frequent drowning during a sequence of dry years may explain an increase in rabbit number observed in previous years. This may make it possible to predict the need for control.

Fruit viability on grubbed Nassella trichotoma (Nees) tussocks

2002 ◽  
Vol 42 (8) ◽  
pp. 1057 ◽  
Author(s):  
S. Lamoureaux ◽  
G. Bourdôt
Keyword(s):  
New Zealand ◽  
High Risk ◽  
Developmental Stage ◽  
Root System ◽  
Seed Bank ◽  
Soil Seed Bank ◽  
Leaf Sheath ◽  
Early Summer ◽  
Late Spring ◽  
Summer Fruit

An experiment was conducted to determine the influence of time of grubbing in the late spring–early summer, panicle developmental stage at grubbing, and the presence or absence of roots on grubbed plants, on the initial and post-senescent viability of fruits of Nassella trichotoma in North Canterbury, New Zealand. The percentage of fruits viable, following desiccation of panicles removed from plants grubbed in the field, increased from 1% for panicles just beginning to emerge from the leaf sheath, to 49% for panicles fully extended at the time of grubbing. Similarly, as grubbing date was delayed from late November (late spring) until late December (early summer), fruit viability increased from 0.3 to 47%. Overall, 36% of the fruits were viable on panicles at the time of grubbing, increasing slightly to 47 and 44%, respectively, after a period of desiccation with and without the panicles being attached to the grubbed plant's root system. It was concluded that if recruitment of fruits of N. trichotoma to the soil seed bank is to be prevented in North Canterbury, plants must be uprooted before panicle extension. Delaying grubbing to when panicles are fully extended, while possibly enabling a higher percentage of plants to be detected and therefore destroyed, carries with it a high risk of permitting the recruitment of viable fruits to the soil seed bank.

A COMPARISON OF RYEGRASS CULTIVARS IN SOUTH CANTERBURY 2. Annual cultivars

1973 ◽  
pp. 219-223
Author(s):  
C.C. Mcleod
Keyword(s):  
New Zealand ◽  
Early Spring ◽  
Early Summer ◽  
Late Spring ◽  
Annual Ryegrass ◽  
Short Rotation

The results of three annual ryegrass cultivar trials showed that, of seven cultivars, the Dutch tetraploid Western Wolths Tewera Barenza established first and made good autumn growth. Three tetraploid Western Wolths cultivars including Grasslands Tama were observed to give the best early spring growth. In contrast, the two later maturing Dutch tetraploid Italian ryegrasses gave the highest late spring and early summer production, Poor maximum total yields, the tetraploid Western Wolths ryegrass Billion was the most consistent cultivar. In addition, the tetraploids, whether Italian or Western Wolths, tended to be more productive than the New Zealand diploid Grasslands Paroa (Ralian) or Gramlands Manawa (short-rotation) ryegrasses.

scholarly journals Productivity and composition of perennial lupin pastures in response to six sowing rates, lime application and lupin type at Glenmore Station, Lake Tekapo

2016 ◽  
Vol 78 ◽  
pp. 139-148
Author(s):  
K.M. Pollock ◽  
D.J. Moot
Keyword(s):  
New Zealand ◽  
Early Summer ◽  
Late Spring ◽  
Lime Application ◽  
Summer Grazing

This study aims to identify the sowing rate necessary to produce lupin dominant and productive pastures in the New Zealand high country under low-moderate fertility, and a regime of late spring/early summer grazing. Blue and Russell lupin were sown on 12 December 2012 at rates of 2, 4, 8, 12, 16 and 32 kg/ha with cocksfoot at 2 kg/ha, and ± 3 t/ha lime. Low lupin sowing rates (

scholarly journals Improving summer and autumn feed quality in New Zealand hill country

2014 ◽  
Vol 76 ◽  
pp. 145-148
Author(s):  
G.M. Rennie ◽  
W.Mcg King ◽  
T.L. Knight ◽  
B. Devantier ◽  
C.J. Hoogendoorn
Keyword(s):  
Early Summer ◽  
Late Spring ◽  
Hill Country ◽  
Pasture Quality ◽  
Herbage Quality ◽  
Dead Material ◽  
Hill Farming ◽  
Cutting Height ◽  
Clover Content

Abstract Management of late spring surpluses to restrict reproductive growth can increase the quality of hillcountry pastures during summer and autumn. This occurs through a reduction in accumulated stem and dead material and an increase in clover content. However, there is little information on the magnitude and longevity of these effects. This trial investigated the effects of four late spring defoliation intensities on herbage quality, measured at the end of spring and during summer. Treatments were applied through regular cutting of hill pastures in areas of medium fertility and slope on two aspects in each of four geo-climatically different hill-farming regions over two years. Pasture herbage quality at the end of spring followed expected trends: defoliation to low residual pasture height led to higher quality herbage. The maximum difference in quality between the lowest cutting height and nil cutting at this time was nearly 2 MJME/kg DM. With a change to uniform cutting height across all plots in early summer, these pasture quality differences reduced and disappeared. Keywords: Pasture quality, hill country, grazing management

scholarly journals Flight behaviour of the manuka chafers, Pyronota festiva (Fabricius) and Pyronota setosa (Given) (Coleoptera: Melolonthinae), on the flipped soils of Cape Foulwind on the West Coast of New Zealand

2018 ◽  
Vol 71 ◽  
pp. 255-261
Author(s):  
Richard J. Townsend ◽  
Jessica E. Dunbar ◽  
Trevor A. Jackson
Keyword(s):  
New Zealand ◽  
West Coast ◽  
Early Summer ◽  
Late Spring ◽  
Field Observations ◽  
The West ◽  
Flight Behaviour ◽  
Sweep Net

Some species in the genus Pyronota are known to be serious pests of pasture. The establishment of new dairy pastures on recently flipped soils on Cape Foulwind, Buller provided a unique opportunity to investigate the flight behaviour and biology of Pyronota festiva and P. setosa from 2008—2012. Flight behaviour was monitored by fixed-vane interruption traps and by field observations. Adults of both species flew through late spring/early summer (Nov—Dec) of each year and seasonal flight timing was consistent between years. Pyronota festiva flight timing and duration were similar to those previously reported in the literature and were slightly female dominated. Pyronota setosa flights started one to two weeks in advance of P. festiva and were dominated by males (>95%). Female P. setosa were rarely observed flying and were rarely caught in sweep-net sampling. Pyronota setosa beetles were never observed swarming or congregating and feeding on the foliage of mānuka. These differences in flight behaviour may help to explain the field observations that P. festiva can rapidly invade new pastures while P. setosa populations appear to spread more slowly.

scholarly journals The effect of deferred grazing in spring and early summer pastures on pasture growth rate and feed quality

2017 ◽  
Vol 79 ◽  
pp. 189-196 ◽  
Author(s):  
B.P. Devantier ◽  
D.R. Stevens ◽  
G.M. Rennie ◽  
K.N. Tozer
Keyword(s):  
Farming Systems ◽  
Early Summer ◽  
Late Spring ◽  
Grazing Management ◽  
Management Tool ◽  
Control Treatment ◽  
Pasture Production ◽  
Hill Country ◽  
Pasture Quality ◽  
Metabolisable Energy

Abstract Maintaining pasture quality in late spring and early summer is a challenge in many hill country farming systems where pasture growth often exceeds animal demand. One possible management tool is to defer grazing on a portion of the farm to enable the desired grazing management and animal performance on the remainder. This study aimed to evaluate the effect of timing and duration of deferred grazing in mid-spring to early-summer on subsequent pasture accumulation rates, composition and quality, from mid-spring through to the following winter. A factorial design (3 durations x 3 closing times) in eight replicates compared withholding grazing (nil, 1 or 3 grazings), in three closing periods, mid spring, late spring, and early summer. Grazing pasture when covers reached 2500 - 3000 kg DM/ha to a residual of 1500 kg DM/ha was the standard grazing regimen used. Grazing after the exclusion period aimed to achieve the same residual as in the control treatment based on a feed budget. Short early closures resulted in little, or no change in pasture quality and quantity for the remainder of the season. Longer closure periods reduced pasture quality due to increases in the proportions of dead and reproductive stem. This effect was reduced with later closings. The control (nil deferred grazings) and mid-spring closings had a net loss of dead matter (-1000 and -420 kg DM/ ha, respectively), while the late -spring and earlysummer closings accumulated 60 and 180 kg DM/ha, respectively. These differences in dead matter were the major driver of the differences of net herbage accumulations (P=0.018), with net accumulations from 7990 kg DM/ha for the control (Nil) closings to 9660 kg DM/ha for the December (late) closings. Deferred grazing can be used to alter feed availability and utilisation while maintaining net pasture production over spring, summer and autumn. Keywords: grazing management, pasture quality, deferred grazing, net pasture accumulation, dead matter, reproductive tillers, metabolisable energy

Natural mortality from poor condition in Atlantic cod (Gadus morhua)

2000 ◽  
Vol 57 (4) ◽  
pp. 826-836 ◽  
Author(s):  
Jean-Denis Dutil ◽  
Yvan Lambert
Keyword(s):  
Gadus Morhua ◽  
Atlantic Cod ◽  
Negative Impact ◽  
Fish Muscle ◽  
Early Summer ◽  
Wild Fish ◽  
Natural Mortality ◽  
Muscle Lactate ◽  
Lactate Dehydrogenase Activity ◽  
Poor Condition

The extent of energy depletion was assessed in Atlantic cod (Gadus morhua) in spring and early summer (1993-1995) to assess relationships between poor condition and natural mortality. Several indices of condition were compared in wild fish in the northern Gulf of St. Lawrence and in fish exposed to a prolonged period of starvation in laboratory experiments. Discriminant analyses classified only a small fraction of the wild fish as similar to cod that did not survive and a much larger fraction as similar to cod that survived starvation. This percentage increased from April to May and peaked in June 1993 and 1994. Condition factor and muscle somatic index allowed a clear distinction between live and dead fish. Muscle lactate dehydrogenase activity suggested that cod had experienced a period of negative growth early in 1993, 1994, and 1995. Fish classified as similar to starved individuals were characterized by a higher gonad to liver mass ratio than others. Reproduction may have a negative impact on survival not only in spring but also later into summer, as some individuals were found not to have recovered by late summer. This study shows that natural mortality from poor condition contributed to lower production in the early 1990s.

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