scholarly journals Reproductive Rates in Lesser Scaup (Aythya affinis) in Southwestern Manitoba: Another Look at the Data

2016 ◽  
Vol 130 (2) ◽  
pp. 110 ◽  
Author(s):  
Gord Hammell
Keyword(s):  
Reproductive Success ◽  
Population Decline ◽  
Food Resources ◽  
Egg Laying ◽  
Aythya Affinis ◽  
The Past ◽  
Age Class ◽  
Lesser Scaup ◽  
Continental Population ◽  
Reproductive Rates

Surveys indicate that Lesser Scaup (Aythya affinis) populations declined during the early 1980s and have since remained below conservation goals. Reasons suggested for the decline include chemical contamination, climate change, and reduced food resources. According to the latter theory, reproductive success of Lesser Scaup has declined because females now arrive on the breeding grounds with fewer nutrient reserves than in the past and this diminished body condition is the result of reduced food resources available at wintering and/or migration areas. To determine whether reproductive success has declined over time, I examined selected Lesser Scaup reproductive rates from 2008 to 2014 in southwestern Manitoba and compared them with those recorded before the continental population decline. Estimated productivity (age class IIa broods/pair), hatching date, Ia and IIa brood size, duckling survival rate (first sighting to age class IIa), and proportion of age class IIa broods with females in attendance were unchanged from values recorded in 1970–1972. Thus, if females are arriving on southern breeding areas with reduced body reserves, they may be recovering these losses before nesting, enabling them to attain reproductive rates similar to those in the past. In addition, these results are consistent with the hypothesis that reduced food resources at non-breeding areas could affect recruitment of southern prairie-parkland breeders to a lesser extent than northern breeders because of the longer time between arrival and egg-laying in the south.

scholarly journals Have Lesser Scaup, Aythya affinis, Reproductive Rates Declined in Parkland Manitoba?

2003 ◽  
Vol 117 (4) ◽  
pp. 582 ◽  
Author(s):  
David N. Koons ◽  
Jay J. Rotella
Keyword(s):  
Local Population ◽  
Population Decline ◽  
Proximate Cause ◽  
Aythya Affinis ◽  
The Past ◽  
Duckling Survival ◽  
Demographic Rates ◽  
Lesser Scaup ◽  
Reproductive Rates

Long-term surveys indicate that the scaup populations have declined over the past 20 years, and that this is probably the result of decreases in Lesser Scaup (Aythya affinis) rather than Greater Scaup (Aythya marila) numbers. To identify factors possibly related to the decline, we estimated demographic parameters for a local population of Lesser Scaup at Erickson, Manitoba, that was well studied before declines occurred and compared these estimates to historic rates. On average, nests were initiated later than in the past, and recent estimates of nesting success and duckling survival were lower than historical estimates. Breeding-season survival of adult females was estimated as 72.6%, with most (83%) mortality occurring during nesting. Current estimates of demographic rates at Erickson are too low to maintain a stable local population, and suppressed reproductive rates might be the proximate cause of the local population decline.

scholarly journals Nutrient Reserves of Lesser Scaup (Aythya Affinis) During Spring Migration in the Mississippi Flyway: A Test of the Spring Condition Hypothesis

The Auk ◽  
2004 ◽  
Vol 121 (3) ◽  
pp. 917-929 ◽  
Author(s):  
Michael J. Anteau ◽  
Alan D. Afton
Keyword(s):  
Reproductive Success ◽  
Body Mass ◽  
Body Condition ◽  
Female Body ◽  
Population Decline ◽  
Spring Migration ◽  
Aythya Affinis ◽  
Lesser Scaup ◽  
Nutrient Reserves ◽  
Mineral Reserves

AbstractThe continental scaup population (Lesser [Aythya affinis] and Greater [A. marila] combined) has declined markedly since 1978. One hypothesis for the population decline states that reproductive success has decreased because female scaup are arriving on breeding areas in poorer body condition than they did historically (i.e. spring condition hypothesis). We tested one aspect of that hypothesis by comparing body mass and nutrient reserves (lipid, protein, and mineral) of Lesser Scaup at four locations (Louisiana, Illinois, Minnesota, and Manitoba) between the 1980s and 2000s. We found that mean body mass and lipid and mineral reserves of females were 80.0, 52.5, and 3.0 g higher, respectively, in the 2000s than in the 1980s in Louisiana; similarly, body mass and lipid and mineral reserves of males were 108.8, 72.5, and 2.5 g higher, respectively. In Illinois, mean body mass and lipid reserves of females were 88.6 and 56.5 g higher, respectively, in the 2000s than in the 1980s; similarly, body mass and lipid and mineral reserves of males were 80.6, 76.0, and 2.7 g higher, respectively. Mean body mass of females were 58.5 and 58.9 g lower in the 2000s than in the 1980s in Minnesota and Manitoba, respectively; mean body mass of males, similarly, were 40.7 g lower in Minnesota. Mean lipid reserves of females in the 2000s were 28.8 and 27.8 g lower than those in the 1980s in Minnesota and Manitoba, respectively. Mean mineral reserves of females in the 2000s were 3.2 g lower than those in the 1980s in Manitoba. Consequently, females arriving to breed in Manitoba in the 2000s had accumulated lipid reserves for 4.1 fewer eggs and mineral reserves for 0.8 fewer eggs than those arriving to breed there in the 1980s. Accordingly, our results are consistent with the spring condition hypothesis and suggest that female body condition has declined, as reflected by decreases in body mass, lipids, and mineral reserves that could cause reductions in reproductive success and ultimately a population decline.

scholarly journals Interactive influences of fluctuations of main food resources and climate change on long-term population decline of Tengmalm’s owls in the boreal forest

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Marek Kouba ◽  
Luděk Bartoš ◽  
Jitka Bartošová ◽  
Kari Hongisto ◽  
Erkki Korpimäki
Keyword(s):  
Climate Change ◽  
Reproductive Success ◽  
Population Decline ◽  
Egg Laying ◽  
Laying Date ◽  
Late Winter ◽  
Aegolius Funereus ◽  
Increasing Temperature ◽  
Tengmalm's Owl

AbstractRecent wildlife population declines are usually attributed to multiple sources such as global climate change and habitat loss and degradation inducing decreased food supply. However, interactive effects of fluctuations in abundance of main foods and weather conditions on population densities and reproductive success have been studied rarely. We analysed long-term (1973–2018) data on Tengmalm’s owl (Aegolius funereus) and the influence of prey abundance and weather on breeding densities and reproductive success in western Finland. We found that fledgling production per breeding attempt declined and laying date of the owl population delayed during the period between 1973 and 2018. The breeding density of the owl population decreased with increasing temperature in winter (October–March), fledgling production increased with increasing temperature and precipitation in spring (April–June), whereas the initiation of egg-laying was delayed with increasing depth of snow cover in late winter (January–March). The decreasing trend of fledgling production, which was mainly due to starvation of offspring, was an important factor contributing to the long-term decline of the Tengmalm’s owl study population. Milder and more humid spring and early summer temperatures due to global warming were not able to compensate for lowered offspring production of owls. The main reason for low productivity is probably loss and degradation of mature and old-growth forests due to clear-felling which results in loss of coverage of prime habitat for main (bank voles) and alternative foods (small birds) of owls inducing lack of food, and refuges against predators of Tengmalm’s owls. This interpretation was also supported by the delayed start of egg-laying during the study period although ambient temperatures increased prior to and during the egg-laying period.

Parasitic laying in nests of gadwalls

1984 ◽  
Vol 62 (4) ◽  
pp. 627-630 ◽  
Author(s):  
James E. Hines ◽  
George J. Mitchell
Keyword(s):  
Reproductive Success ◽  
Differential Effect ◽  
Nesting Success ◽  
Nest Density ◽  
Aythya Affinis ◽  
Lesser Scaup ◽  
Anas Strepera ◽  
Intraspecific Parasitism

At Waterhen Marsh, Saskatchewan, at least 60 (17%) of 355 completed gadwall (Anas strepera) clutches were parasitized by other gadwalls (9%), lesser scaup (Aythya affinis) (8%). or both species (< 1%). Nests known to be parasitized by gadwalls contained on average at least 7 or 8 parasitic eggs while those parasitized by scaup contained an average of only 1.6 ± 0.2 (SE) parasitic eggs. Most parasitized nests were situated in areas of high nest density. Lesser scaup laid parasitically in gadwall nests located in shorter or sparser cover than most other nests, whereas nests parasitized by gadwalls were in vegetation similar to unparasitized nests. Assuming that nests parasitized by gadwalls contained > 14 eggs, intraspecific parasitism significantly reduced nesting success from 76 to 54%, egg success from 74 to 45%, and hatchability of eggs from 97 to 91%. Interspecific parasitism had no significant effect on nesting success or hatchability, but caused a slight decrease (74 to 67%) in egg success. The differential effect of lesser scaup and gadwall parasitism on host reproductive success was likely due to differences in numbers of parasitic eggs laid in the nest of the host by each species. We hypothesize that parasitism occurred because ducks did not continuously occupy the nest during laying, thereby allowing two or more females to lay eggs synchronously at the same site. Parasitic laying by gadwalls was possibly an anomaly, rather than true parasitism.

Lesser Scaup (Aythya affinis)

2014 ◽  
Author(s):  
Michael J. Anteau ◽  
Jean-Michel DeVink ◽  
David N. Koons ◽  
Jane E. Austin ◽  
Christine M. Custer ◽  
...  
Keyword(s):  
Aythya Affinis ◽  
Lesser Scaup

Beyond the austerity-driven hypothesis: Political economic theses on penality and the recent prison population decline

2021 ◽  
pp. 147737082110006
Author(s):  
José A. Brandariz
Keyword(s):  
Prison Population ◽  
Population Decline ◽  
Theoretical Frameworks ◽  
The Past ◽  
Economic Forces ◽  
Global North ◽  
Economic Perspectives ◽  
Political Economic ◽  
The Impact ◽  
Spending Cuts

In what might be called the ‘austerity-driven hypothesis’, a consistent strand of literature has sought to explain the prison downsizing witnessed in many jurisdictions of the global north over the past decade by referring to the financial crisis of the late 2000s to early 2010s and its effects in terms of public spending cuts. Since this economic phase is essentially over, whereas the (moderate) decarceration turn is still ongoing, there are good reasons to challenge this hypothesis. This article delves into the non-economic forces that are fostering a prison population decline that, 10 years on, is becoming the new ‘penal normal’. The article thereby aims to spark a dialogue not only with the scholarship exploring the prison downsizing but also with certain theoretical frameworks that have played a key role in examining the punitive turn era. Additionally, the article contributes to the conversation on the need to reframe materialist readings on penality in a ‘non-reductionist’ fashion. By revisiting heterodox theses and scrutinizing the impact of recent penal changes on traditional materialist accounts, the article joins the collective endeavour seeking to update political economic perspectives on punishment and the penal field.

Hepatic Element Concentrations of Lesser Scaup (Aythya affinis) During Spring Migration in the Upper Midwest

2010 ◽  
Vol 61 (1) ◽  
pp. 144-150 ◽  
Author(s):  
Angela E. Pillatzki ◽  
Regg D. Neiger ◽  
Steven R. Chipps ◽  
Kenneth F. Higgins ◽  
Nancy Thiex ◽  
...  
Keyword(s):  
Spring Migration ◽  
Upper Midwest ◽  
Aythya Affinis ◽  
Element Concentrations ◽  
Lesser Scaup

Eyeworm infections ofOxyspirura petrowi, Skrjabin, 1929 (Spirurida: Thelaziidae), in species of quail from Texas, New Mexico and Arizona, USA

2016 ◽  
Vol 91 (4) ◽  
pp. 491-496 ◽  
Author(s):  
N.R. Dunham ◽  
R.J. Kendall
Keyword(s):  
New Mexico ◽  
Population Decline ◽  
Northern Bobwhite ◽  
Cellular Damage ◽  
Scaled Quail ◽  
Callipepla Squamata ◽  
The Past ◽  
New Research ◽  
Gambel's Quail ◽  
Historical Range

AbstractNorthern bobwhite (Colinus virginianus) and Scaled quail (Callipepla squamata) have been declining steadily throughout much of their historical range over the past few decades. Even the Rolling Plains of Texas, historically rich with wild quail and one of the last remaining quail strongholds, has been suffering a population decline, most notably since 2010. Gambel's quail (Callipepla gambelii) have also been experiencing their own decline throughout their respective range, but not as significant as that of other species of quail. Eyeworms (Oxyspirura petrowi) in quail have been recognized for years but not thoroughly studied until recently. New research reveals thatO. petrowiinfection can cause inflammation, oedema, and cellular damage to the eye of the quail host. The objective of this research was to better understand the prevalence of the eyeworm infection in different quail species, expand on known distribution, and determine if there is a relationship between location and species infected with eyeworms. Northern bobwhite, Scaled quail and Gambel's quail were hunter-donated from one county within Texas, New Mexico and Arizona, and examined for the prevalence, mean abundance and mean intensity of eyeworm infection from November 2013 to February 2014. Quail from every location were found to have individuals with a varying degree of eyeworm infection. This is the first study to document eyeworm infection in Gambel's quail and in quail in New Mexico and Arizona, and reports the highest eyeworm infection found in Northern bobwhite and Scaled quail.

Breeding biology of the Critically Endangered Tahiti MonarchPomarea nigra, a bird with a low productivity

2017 ◽  
Vol 28 (4) ◽  
pp. 606-619 ◽  
Author(s):  
CAROLINE BLANVILLAIN ◽  
THOMAS GHESTEMME ◽  
TEHANI WITHERS ◽  
MARK O’BRIEN
Keyword(s):  
Reproductive Success ◽  
French Polynesia ◽  
Egg Laying ◽  
Breeding Biology ◽  
Critically Endangered ◽  
Tropical Island ◽  
Island Endemics ◽  
Nest Activity ◽  
Considerable Length ◽  
One Year

SummaryWe studied the breeding biology of Tahiti MonarchPomarea nigra, a ‘Critically Endangered’ forest bird endemic to Tahiti (French Polynesia). Nest activity was monitored from 1998 to 2002, and again from 2008 to 2015. During these 12 years, only 2–13 breeding pairs per year produced hatchlings. Egg-laying occurred all year, but usually increased between August and January, peaking around November. Of the 200 nests monitored, 33 (16%) were abandoned shortly after construction, 71 had an egg laid immediately after the nest were completed (34 %) and 96 nests (46 %) had a pre-incubation phase of 18.9 ± 1.9 days (3–62 days;n= 47 nests), during which the birds visited the nest on an irregular basis. Half (49 of 96) of these nests were abandoned before an egg was laid, with incubation subsequently commencing at the remaining nests (n= 47). Although both sexes incubated for an average of 13.6 ± 0.3 days (range 13–15), the female usually spent more time incubating than the male. Only one young per nest was ever observed. The average nestling phase was 15.5 ± 0.7 days (range 13 to 20 days). Parents continue to feed the young after fledging for 74 ± 4.7 days (range 42–174). As with many tropical island endemics, the Tahiti Monarch has low reproductive productivity as indicated by the fact that: 1) only 56% of pairs attempt to lay an egg in any one year, 2) most pairs attempt only one brood per year and 3) the considerable length of the nesting and fledging phases. Because of its low productivity, maximising the reproductive success of the Tahiti Monarch is essential to secure its recovery.

Female, but not male, agonistic behaviour is associated with male reproductive success in stable bluebanded goby (Lythrypnus dalli) hierarchies

Behaviour ◽  
2014 ◽  
Vol 151 (10) ◽  
pp. 1367-1387 ◽  
Author(s):  
Tessa K. Solomon-Lane ◽  
Madelyne C. Willis ◽  
Devaleena S. Pradhan ◽  
Matthew S. Grober
Keyword(s):  
Reproductive Success ◽  
Egg Laying ◽  
Dominant Male ◽  
Male Reproductive Success ◽  
Agonistic Behaviour ◽  
Social Species ◽  
Evolution Of Sociality ◽  
Lythrypnus Dalli ◽  
Linear Hierarchies ◽  
Substantial Control

In many social species, there are important connections between social behaviour and reproduction that provide critical insights into the evolution of sociality. In this study, we describe associations between agonistic behaviour and male reproductive success in stable social groups of bluebanded gobies (Lythrypnus dalli). This highly social, sex-changing species forms linear hierarchies of a dominant male and multiple subordinate females. Males reproduce with each female in the harem and care for the eggs. Since aggression tends to be associated with reduced reproduction in social hierarchies, we hypothesized that males in groups with high rates of aggression would fertilise fewer eggs. We also hypothesized that a male’s agonistic behaviour would be associated with his reproductive success. Dominants often exert substantial control over their harem, including control over subordinate reproduction. To address these hypotheses, we quantified egg laying/fertilisation over 13 days and observed agonistic behaviour. We show that there was a significant, negative association between male reproductive success and the total rate agonistic interactions by a group. While no male behaviours were associated with the quantity of eggs fertilised, female agonistic behaviour may be central to male reproductive success. We identified a set of models approximating male reproductive success that included three female behaviours: aggression by the highest-ranking female and approaches by the lowest-ranking female were negatively associated with the quantity of eggs fertilised by males in their groups, but the efficiency with which the middle-ranking female displaced others was positively associated with this measure. These data provide a first step in elucidating the behavioural mechanisms that are associated with L. dalli reproductive success.

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