South Okanagan Research Articles

Field Investigation into Tree Fates from Recent Apple Tree Decline: Abrupt Hydraulic Failure Versus Gradual Hydraulic Loss

In the last decade, a sporadic tree health syndrome affecting high-density apple plantings in North America has become known as Rapid Apple Decline (RAD) or Sudden Apple Decline (SAD). The affected apple trees were typically grafted on small dwarfing rootstocks, often displayed necrosis at the graft union, and suffered from sudden mortality that occurred over 2–3 weeks amid the growing season or a gradual decline. In 2019 and 2020, we conducted a multi-site investigation in the south Okanagan, British Columbia, Canada, to assess the stem hydraulic characteristics, stomatal conductance, leaf δ13C‰, and fruit dry matter accumulation of the declining trees during disease progression. In trees that died, mortality appeared to be associated with severe disruption in xylem water transport at the damaged graft union, followed by abrupt hydraulic failure. In contrast, symptomatic trees that did not die exhibited the moderately declined plant water relations and a reduction in fruit dry matter accumulation followed by either further deterioration or eventual recovery. This pattern indicates the risk of carbohydrate depletion over gradual hydraulic decline and the importance of timely horticultural remedies. In the present study, we discuss potential horticultural practices to mitigate hydraulic dysfunctions and enhance crop tolerance.

Migration ecology of western gray catbirds

BackgroundFor many songbirds in North America, we lack movement details about the full annual cycle, notably outside the breeding season. Understanding how populations are linked spatially between breeding and overwintering periods (migratory connectivity) is crucial to songbird conservation and management. We assessed migratory connectivity for 2 breeding populations of Gray Catbirds (Dumetella carolinensis) west of and within the Rocky Mountains by determining migration routes, stopover sites, and overwintering locations. Additionally, we compared apparent annual survivorship for both populations.MethodsWe deployed 39 archival light-level geolocators and 21 Global Positioning System (GPS) tags on catbirds in the South Okanagan Valley, British Columbia, Canada, and 32 geolocators and 52 GPS tags in the Bitterroot River Valley, Montana, USA. These devices allowed us to determine migration routes, stopover sites, overwintering locations, and migratory connectivity. Migratory connectivity was quantified using Mantel’s correlation. We used mark-recapture of colour banded catbirds in both sites to estimate apparent annual survivorship.ResultsWe retrieved 6 geolocators and 19 GPS tags with usable data. Gray Catbirds from both populations passed through the Rocky Mountains eastward before heading south towards their overwintering locations in northeastern Mexico and Texas. Stopover sites during fall migration occurred primarily in Montana, Kansas, Oklahoma, and Arkansas. Overwintering locations spanned Texas and 5 states in northeastern Mexico. Individual catbirds used up to 4 distinct sites during the overwintering period. Catbirds separated by almost 500 km during the breeding season overlapped during the non-breeding season, suggesting weak migratory connectivity among western populations (Mantel’s correlation = 0.013, P-value = 0.41). Catbird apparent annual survivorship estimates were higher in British Columbia (0.61 ± 0.06 females; 0.64 ± 0.05 males) than in Montana (0.34 ± 0.05 females; 0.43 ± 0.04 males), though the main driver of these differences remain unclear.ConclusionsOur results provide high precision geographic details during the breeding, migration, and overwintering phases of the annual cycle for western Gray Catbirds. Notably, we found that western catbirds followed the Central Flyway as opposed to the Pacific Flyway. We document that catbirds used multiple sites over winter, contrary to the popular belief that this phase of the annual cycle is stationary for most songbirds.

Rural Food and Wine Tourism in Canada’s South Okanagan Valley: Transformations for Food Sovereignty?

This interdisciplinary research analyses the relationships between food sovereignty principles and food and wine tourism in rural contexts by asking how rural tourism stakeholders understand these concepts, mobilize the interrelationships, and to what purpose. Wine and food tourism is one of the fastest-growing rural tourism niches, with effects on the orientation of food systems, the livelihoods of producers, the viability of rural communities, and the biophysical environment. Secondary research and semi-structured interviews provide insights into how qualities of food sovereignty transitions are conceptualized, recognized, developed, supported, and promoted in the case of British Columbia’s South Okanagan Valley. An appreciative approach was used because this research aims to understand rural food and wine tourism’s potential contribution to food sovereignty. Although the term ‘food sovereignty’ did not resonate for most participants, qualities of a transition towards food sovereignty such as reorienting agriculture, food processing and consumption to the local region, supporting rural economies and environmental sustainability were considered integral to rural food tourism. Participants saw future opportunities for rural food and wine tourism to serve broader transformative purposes that would benefit locals, visitors, and the environment. Research results could be used to inspire critical academic, community and policy dialogue about food sovereignty in wine and food tourism destinations.

Reconnecting Amphibian Habitat through Small Pond Construction and Enhancement, South Okanagan River Valley, British Columbia, Canada

The arid south Okanagan River Valley, British Columbia is a highly-modified landscape; where wetland and riparian habitat loss exceeds 85%, and 88% of remaining wetlands experience at least one harmful anthropogenic stressor. This multi-stressor landscape for amphibian species at risk led to a collaborative stakeholder approach for habitat restoration and species recovery. The main project goal was to increase the quantity and quality of lowland wetland habitat by reconnecting known amphibian-breeding sites with constructed and/or enhanced small ponds. Long-term amphibian monitoring data were used to determine strategic locations for wetland construction and/or enhancement. Habitat enhancement outcomes (Ntotal = 21 sites) since 2006 include 10 newly constructed ponds, enhancement of eight re-contoured ponds after historic infilling, and invasive predatory species removal at three sites. Project ponds were monitored annually (2007 to 2014) for calling frogs, the presence of eggs, and metamorphic emergence. Early signs of colonization and metamorphic success for Great Basin Spadefoot (Spea intermontana) (N = 13 sites) and Pacific treefrog (Pseudacris regilla) (N = 7 sites) populations have been observed, however no records of Blotched tiger salamanders (Ambystoma mavortium) colonization has been detected. Wetland habitat construction and enhancement have doubled the number of available fishless ponds to support breeding within the study area and engaged landowners through voluntary stewardship. Whether constructed or enhanced ponds have aided species recovery is unclear, though the colonization and successful metamorphosis of some species provides early supporting evidence that it will.

Aboriginal Rights Litigation, Negotiation, and Practice among the Metis of BC: Community Perspectives on Creating Legal Change

This paper examines the perspectives of Metis people in the southern BC interior about how to deal with the rejection by the courts of all three Metis rights claims in the province. The perspectives of those directly involved in the three cases, along with community members in the subject areas (Thompson/Shuswap, south Okanagan, Kootenays) reveal that people generally prefer negotiation to litigation in the BC context, as lack of understanding of Metis history, territories and communities in BC creates difficulties for BC Metis litigants. Negotiation was viewed favourably by participants, but continuing to practise rights was seen as more important than gaining state recognition of rights.

ALWAYS COMING HOME: METIS LEGAL UNDERSTANDINGS OF COMMUNITY AND TERRITORY

Metis ideas of territory are complex, varied and often not well understood. Metis perspectives on intersections of territory and community are likewise not appreciated by Canadian courts. This is evident in the difficulties of Metis rights claimants in British Columbia, where misconceptions about Metis history and traditional use areas have resulted in courts questioning the existence of historic Metis communities in the province. The leading case on Metis rights in Canada, R v Powley, requires claimants to prove there is a historic Metis community in an area where claimed rights are exercised. In BC, courts following Powley in three cases – R v Howse, R v Nunn and R v Willison – have held there are no historic Metis communities in the Kootenays, the south Okanagan, or the Kamloops/Shuswap area. Although these regions comprise only a portion of lands within provincial boundaries, the BC government takes the position there are no Metis communities in the province capable of meeting the Powley test, and thus asserts there can be no Metis Aboriginal rights holders in BC.
 To challenge this position, and in order to illustrate the multiplicity and richness of Metis legal understandings of territory and community, the author braids family history, narrative, legal analysis and the perspectives of 23 Metis people from the southern BC interior who were involved in or affected by the Howse, Nunn and Willison cases. The author suggests that expansive and nuanced Metis understandings of communities and territories cannot be encompassed by the Powley/Willison definition of a Metis community as “... a group of Métis with a distinctive collective identity, living together in the same geographic area and sharing a common way of life”. While the court’s definition posits history, territory and community as separable, Metis views suggest these concepts are interlinked and mutually constitutive.

Multiple Broods and Nest Success in Western Yellow-breasted Chats (Icteria virens auricollis) in the south Okanagan Valley, British Columbia, Canada

ABSTRACT During 2005–2010, we observed color bands on adult birds to discover one instance of triple brooding and multiple cases of double brooding in western Yellow-breasted Chats (Icteria virens auricollis) in the south Okanagan Valley, British Columbia (BC), Canada at the northern periphery of their breeding range. In the case of the triple brood, the first and second broods successfully fledged chats but the third brood failed. During the same period, 4.7% of banded females had double broods. Another 32 unidentified females for whom we are confident were the same females who initiated the first brood, also had double broods. If these females are included, 13% of chats had double broods. During 2002–2010, 57.8% first brood nests were successful and during 2005–2010, 69.2% second brood nests were successful.

Clutch Size in the Great Basin Spadefoot (Spea intermontana), South Okanagan Valley, British Columbia, Canada

Breeding wetlands and upland terrestrial habitat used by the Great Basin Spadefoot (Spea intermontana) are under intense pressure from the expansion of agriculture, urban development, and loss of grasslands throughout the species range (AmphibiaWeb 2012). At the northern edge of the Spea intermontana geographic range, the British Columbia population of the Great Basin Spadefoot is designated as a threatened Species At Risk (BC Southern Interior Reptile and Amphibian Recovery Team 2007; Committee on the Status of Endangered Wildlife in Canada [COSEWIC] 2007). In the South Okanagan Valley, British Columbia, approximately 90% of wetlands have been lost (Lea 2008). In the lowland Valley (,450 m elevation), metamorphic success of Spea intermontana has been observed in natural ephemeral wetlands, small agricultural ponds, and diverse anthropogenic sites (Ashpole and others 2012). Spadefoot developmental adaptation (either a delay or an increased rate of metamorphosis) in response to the larval habitat has been attributed to resource availability and consequently fitness (see overview by Morey and Reznick 2004). Morey and Reznick (2004) report wild populations of Spea intermontana development ranging from 36 to 60 d. In a comparative resource study, Spea intermontana metamorphic development was slowest (41 d) in individuals with the lowest food availability (Morey and Reznick 2004). Spea intermontana clutches are described in standard field guides as containing few eggs (5 to 40 eggs/clutch) in a randomly shaped grape-sized cluster, where 1 egg can easily be detached from the group (Corkran and Thoms 1996; Cannings and others 1999; Jones and others 2005; Matsuda and others 2007). Here we describe large clutch sizes of Spea intermontana not previously documented in the scientific literature or field guides. Egg clutches were oviposited in 3 human-made ‘ephemeral’ breeding sites, including a swimming pool (Site A), a constructed agricultural retention pond (Site B), and a cement irrigation ditch (Site C). Additionally, road kill samples of Spea intermontana provide a broader range of possible fecundity rates, and skeletocronology suggests that reproductive maturity occurs at 1 y of age.

"Okanagan Geology South: Geologic Highlights of the South Okanagan Valley, British Columbia" edited by Murray A. Roed and Robert J. Fulton. 2011. [book review

"Okanagan Geology South: Geologic Highlights of the South Okanagan Valley, British Columbia" edited by Murray A. Roed and Robert J. Fulton. 2011. [book review

Okanagan geology south. Geologic highlights of the South Okanagan Valley, British Columbia edited by Murray A. Roed and Robert J. Fulton

Okanagan geology south. Geologic highlights of the South Okanagan Valley, British Columbia edited by Murray A. Roed and Robert J. Fulton

Habitat Selection and Reproductive Success of Lewis's Woodpecker (Melanerpes lewis) at Its Northern Limit

Lewis's Woodpecker (Melanerpes lewis) has experienced population declines in both Canada and the United States and in 2010 was assigned a national listing of threatened in Canada. We conducted a two-year study (2004–2005) of this species at its northern range limit, the South Okanagan Valley in British Columbia, Canada. Our main objective was to determine whether the habitat features that influenced nest-site selection also predicted nest success, or whether other factors (e.g. cavity dimensions, clutch initiation date or time of season) were more important. Nest tree decay class, density of suitable cavities and total basal area of large trees were the best predictors of nest-site selection, but these factors were unrelated to nesting success. Estimates of demographic parameters (mean ± SE) included daily nest survival rate (0.988±0.003, years combined), nest success (0.52±0.08), clutch size (5.00±0.14 eggs), female fledglings per successful nest (1.31±0.11), and annual productivity (0.68±0.12 female fledglings per nest per year). Although higher nest survival was associated with both early and late initiated clutches, early-initiated clutches allowed birds to gain the highest annual productivity as early clutches were larger. Nests in deep cavities with small entrances experienced lower predation risk especially during the peak period of nest predation. We concluded that nest-site selection can be predicted by a number of easily measured habitat variables, whereas nest success depended on complicated ecological interactions among nest predators, breeding behaviors, and cavity features. Thus, habitat-based conservation strategies should also consider ecological factors that may not be well predicted by habitat.

Unexplained Die-Off of Larval Barred Tiger Salamanders (Ambystoma mavortium) In An Agricultural Pond In the South Okanagan Valley, British Columbia, Canada

The Southern Mountain population of the Barred Tiger Salamander (Ambystoma mavortium) is federally listed in Canada as endangered (Southern Interior Reptile and Amphibian Recovery Team 2008; Species at Risk Public Registry http:/ / www.sararegistry.gc.ca/ species/ speciesDetails_e.cfm?sid=697; listed as Ambystoma tigrinum prior to name change in 2010). This population is restricted to the South Okanagan, Lower Similkameen, and Kettle River watersheds in British Columbia (Sarell 1996, 2004; Southern Interior Reptile and Amphibian Recovery Team 2008). A decline in the geographic range of the Barred Tiger Salamander in the interior of British Columbia during the past 30 y is inferred from apparent extirpations at historic breeding sites, combined with extensive habitat loss (Lea 2008). As of August 2005, only 57 occupied breeding sites were known in British Columbia (BCMOE 2005; Southern Interior Reptile and Amphibian Recovery Team 2008). We report here on the incidence of a die-off of Barred Tiger Salamanders and the consequences that multiple stressors and isolation have on the potential for population recovery at this site. We conducted a survey of amphibians from 2003 to 2006 to determine amphibian use of ponds within the lowland valley and intensive agricultural zone of the south Okanagan Valley. Wetlands from Okanagan Falls to Osoyoos were surveyed for occupancy by amphibians. Barred Tiger Salamanders were found at only 8 of the 96 ponds surveyed. A pond (Pond #1) near Osoyoos, within an orchard and vineyard farm, was first surveyed in 2003. The pond holds water permanently and is approximately 5 m deep, 95 m long, and 73 m wide. Between 9 and 25 June, we surveyed the pond on 3 occasions using floating minnow traps set overnight, and on 5 occasions using daytime time-constrained dip-net searches (Table 1). Barred Tiger Salamanders observed 9 to 12 June were alive ( n = 28 larvae), and none showed signs of ill health. On 19 June, however, 4 living and 4 dead larvae were observed in traps. On 23 and 24 June, only dead and floating Barred Tiger Salamander larvae were observed in the pond (ntotai = 13 larvae). Due to extreme decomposition at the time of collection, samples of the larvae were not collected or examined to

Genetic mating system and population history of the endangered Western Yellow-breasted Chat (Icteria virens auricollis) in British Columbia, Canada

The Western Yellow-breasted Chat ( Icteria virens auricollis (Deppe, 1830)) is a Neotropical migrant, with a Canadian distribution restricted to breeding populations in southern British Columbia. Given its small population size and diminishing breeding habitat, Yellow-breasted Chats are federally endangered in Canada. We used genotypic data at eight microsatellite loci to assess genetic diversity, reconstruct population structure and demographic history, and characterize genetic mating system of Yellow-breasted Chats sampled across 60 nesting sites at five locations in the Okanagan Valley (n = 148). Microsatellite-based analyses indicated lack of significant genetic differentiation among breeding sites and no genetic evidence of population decline. Parentage assignments indicated moderate levels of extra-pair paternity, with 30.7% offspring not sired by attending males. Patterns of sibship among nestlings revealed 49.1% of the clutches were composed entirely of full-siblings, with half-siblings and unrelated nestlings present in some broods. These findings suggest that extra-pair paternity is common in Yellow-breasted Chats, similar to other avian species, and present the first evidence of conspecific brood parasitism in warblers. Our findings add to a growing body of research informing the need to establish a national park in the south Okanagan to preserve critical habitat and connect populations of species at risk.

Habitat Characterization of Breeding Territories of the Western Yellow-Breasted Chat in the South Okanagan, British Columbia, Canada

From 2002 to 2007 we measured breeding territory, nest patch, and nest shrub characteristics for Yellow-breasted Chats (Icteria virens auricollis) in the northern edge of their distribution in British Columbia, Canada. Surveys were done at 94 breeding territories, 238 nest patches, 246 nest shrubs, and at random locations for comparison. Habitat selection by chats was not random, and territories were selected for specific vegetation characteristics. Chat breeding territories were located in lower elevation riparian zones consisting mainly of dense shrubs and early successional water-tolerant trees, with the dominant shrub species being wild rose (Rosa spp.). Chats nested in 12 plant species and 72% of nests were within wild rose, which was also the dominant species in 5 m and 11.3 m radius nest patch plots centered at the nest shrub. Based on georeferenced locations of male chat singing or perching locations, chat breeding territories were on average 0.37 ha (s = 0.27 ha) in size (n = 66).

Hatching success and pesticide exposures in amphibians living in agricultural habitats of the South Okanagan Valley, British Columbia, Canada (2004–2006)

In 2004 to 2006, in the Okanagan Valley, British Columbia, Canada, we measured pesticides, water chemistry, and hatching success of Great Basin spadefoot (Spea intermontana), Pacific treefrog (Pseudacris regilla), Western toad (Bufo boreas), and Columbia spotted frog (Rana luteiventris). Predator-proof cages containing Gosner Stage 4 eggs were placed in ponds in nonagricultural reference sites in conventionally sprayed and organic orchards. Seventeen pesticides were detected in ponds in sprayed orchards but occurred at low concentrations (ng/L) except for diazinon (1,410 ng/L). Chloride, sulfate, conductivity, nitrate, and phosphorus showed significant differences among sites. Spadefoot mean hatching success ranged from 0 to 92% among sprayed orchards, whereas the range was 48 to 98.6% among organic orchards and 51 to 95.5% among reference sites. Mean hatching success for Pacific treefrog was 22.1 to 76.1% among sprayed orchards, whereas the range was 83.4 to 97.1% among reference sites. Although sample sizes were small and replication was low, we found that trends in hatching success of eggs of Western toad and Columbia spotted frogs were consistent with the other species. Variables that correlated negatively with amphibian hatching success included 12 pesticides and seven water chemistry parameters. However, stepwise regression found that, in 2005, atrazine accounted for 79% of the variation in spadefoot hatching success and, in 2006, atrazine, total nitrate, and chlorpyrifos accounted for 80%. For Pacific treefrog there were no significant correlations with pesticide concentrations; rather, hatching success correlated with water chemistry parameters. The present study also emphasizes the variability in species sensitivity and importance of incorporating water chemistry into the interpretation of water quality for amphibians.

Comparing approaches for modeling spatially distributed direct recharge in a semi-arid region (Okanagan Basin, Canada)

Spatially distributed recharge is compared at two different scales using three different modeling approaches within the semi-arid Okanagan Basin, British Columbia, Canada. Regional recharge was modeled by mapping results for one-dimensional soil columns from the water-balance code HELP (Hydrologic Evaluation of Landfill Performance, V3.80D). The regional model was then compared to two, independently derived, local-scale models to ensure local trends were captured in the regional model, and to compare modeling methods. Average annual recharge, predicted by the regional model, varied from no recharge to 186 mm/yr. For the north Okanagan (Vernon area), regional estimates were compared to Richards’ equation-based MIKE-SHE (V2007) estimates, which showed a significant difference in average annual recharge: 7 mm/yr (MIKE-SHE) and 109 mm/yr (HELP). In the south Okanagan (Oliver area), regional estimates were compared to high-resolution, local HELP estimates. Similar values of average annual recharge were obtained: 34 mm/yr (local) and 42 mm/yr (regional). A comparison with measured actual evapotranspiration data in the north Okanagan, showed HELP over-predicted recharge compared to MIKE-SHE by under-predicting evapotranspiration during summer months. Thus, the use of HELP in semi-arid areas may be limited if accurate estimates of recharge are needed. However, results may give satisfactory groundwater model calibrations results because of high uncertainty in hydraulic properties.

First Record of Xiphinema pacificum from a Peach Orchard in Georgia.

In April 2000, a Xiphinema sp. was found in a peach (Prunus persica (L.) Batsch) orchard during a longidorid nematode survey in Concord, GA. The nematode was recovered from the rhizosphere of healthy and dying peach trees established on Lovell rootstock. Following a comparative microscope study, the species was identified as X. pacificum Ebsary, Vrain, & Graham, a putative species of the X. americanum group (2). All morphometric measurements coincided with the original description (1). In North America, this group of nematodes are natural vectors of four economically important nepoviruses that are responsible for causing substantial damage to a wide variety of crops. In spring 1999, tree death from bacterial canker (Pseudomonas syringae pv. syringae) occurred within this then 2-year-old orchard. Samples showed that populations of X. pacificum and Pratylenchus sp. were greater under dying trees (34 and 143/100 cm3 of soil) than under healthy trees (19 and 30/100 cm3 of soil), respectively. Samples taken during the 2000 survey contained 10 X. pacificum per 100 cm3 soil under apparently healthy trees. This nematode was originally described from British Columbia, Canada, where it seemed to be restricted in its distribution to vineyards in the south Okanagan Valley. To our knowledge, this is the first report of X. pacificum in the United States.

Browsing of Antelope Bitterbrush(Purshia tridentata: Rosaceae) in the South Okanagan Valley, British Columbia: Age Preferences and Seasonal Differences

We compared browsing on twigs of small and large antelope bitterbrush (Purshia tridentata) shrubs among ten sites in the south Okanagan valley, British Columbia. We tested whether there were any age preferences by browsers and determined whether these preferences changed between seasons and mode of browsing. Two different types of browsing were observed: leaf stripping which occurred in the summer and twig clipping which occurred predominantly in the winter. We calculated age and size relationships showing that shoot volume and especially stem diameter were good predictors of shrub age. Among the ten sites, clipping removed 0.02 to 15.7% of a shrub's total twig length and stripping removed leaves from 0 to 5.2% of total twig length. Observations suggested that California bighorn sheep (Ovis canadensis california) stripped antelope bitterbrush leaves in late summer, mule deer (Odocoileus hemionus hemionus) clipped twigs in the winter and cattle clipped twigs in the summer. Browsers preferred to clip twigs on smaller and hence younger antelope bitterbrush shrubs. In contrast, larger and older shrubs were preferred for leaf stripping. Since twig clipping was more prevalent than leaf stripping in antelope bitterbrush, overall preference for younger shrubs may lead to difficulties in seedling establishment in regions where it is heavily used as winter forage.

Twinning in Bighorn Sheep

Twelve bighorn ewes (Ovis canadensis), killed by vehicular traffic in southern British Columbia, were examined for pregnancy; 11 were pregnant, 4 of them were carrying twins. The absence of twins among bighorn sheep frequently has been noted by biologists recording their field observations. A recent author (Woodgerd, W. 1964. Population dynamics of bighorn sheep on Wildhorse Island. J. Wildl. Mgmt. 28(2):381391) summarized his own observations of a bighorn sheep population on Wildhorse Island (Montana) plus a literature review of six authors and could find only one reference to an authentic twin birth among bighorn sheep. The following observations suggest that twins may occur more frequently than published data indicate. An opportunity to examine reproductive tracts from bighorn sheep arose during the winter of 1963-64. Heavy snows forced wintering ewes and lambs down along Highway 97 in the vicinity of Vaseux Lake (Okanagan Valley) in southern British Columbia. During a 4-month period from Table 1. Age and frequency of single and twin pregnancies in female sheep killed by traffic in the vicinity of Vaseux Lake, British Columbia. AGE NUMBER NOT PREGNANT (YEARS)* EXAMINED PREGNANT Single Twins Single Twins 3 4 1 2 1 4 5 2 3 5 1 1I 6 2 2 * Age determined by growth rings on horns (Taber, R. D. 1963. Criteria of sex and age. Pages 184-186. In Henry S. Mosby (Editor), Wildlife investigational techniques. Printed for The Wildlife Society by Edwards Brothers, Inc., Ann Arbor, Michigan. xxiv -+419 pp.) late November, 1963, until late March, 1964, 13 ewes were killed by highway traffic. During the winter of 1964-65 two more ewes were killed in the area. Table 1 summarizes information about age and rate of pregnancy of 12 sheep collected and examined by members of British Columbia's Fish and Game Branch in the south Okanagan. Twelve ewes were examined for pregnancy and in four cases twins were found. The most advanced twin pregnancy was observed February 15, approximately 2 months before lambing, which begins during mid-April. All twin fetuses appeared healthy. One 6-year-old ewe, killed February 6, 1964, had an extra-uterine male fetus attached to the right body wall within the abdominal cavity. I was unable to examine his specimen, but it was reported that the fetus appeared normal in its development but was tightly enclosed within the fetal membranes. Observations of the Vaseux herd are limited but an occurrence of live twins has never definitely been established. On June 18, 1964, a coyote was observed harrying a group of ewes and lambs. One ewe and two lambs consistently remained together and in one instance left the main group of sheep and moved out onto a small ledge which provided b tter protection from the coyote. These lambs may have been twins. Received for publication July 6, 1965.

INCREASE IN SEED PRODUCTION FROM NITROGEN FERTILIZATION OF NATIVE BEARDLESS WHEATGRASS

Nitrogen fertilization greatly increased pure seed yield of native beardless wheatgrass, Agropyron inerme, where the mean annual precipitation was 11 inches in the South Okanagan area of British Columbia. In one experiment in 1959, ammonium nitrate broadcast at 450 pounds of actual nitrogen per acre increased seed yield from 3.5 pounds per acre for the unfertilized plots to 17.5 pounds, a maximum increase of 400 per cent. One hundred and fifty pounds of actual nitrogen per acre increased seed yield 330 per cent and the 50-pound rate increased the yield of seed 140 per cent. At two other locations in 1961, unfertilized plots yielded 18.8 pounds of seed per acre; 150 pounds of actual nitrogen per acre increased seed yield to 59.2 pounds and the 50-pound treatment produced 46.5 pounds of seed per acre. Yield increases resulted from increases in spike production because weight of seed per spike was not increased by fertilization. Germination was not affected and per cent pure seed was slightly increased by the nitrogen treatments. This increase in seed production is considered favorable for the restoration of preferred species on depleted native range.