Have Lesser Scaup, &lt;em&gt;Aythya affinis&lt;/em&gt;, Reproductive Rates Declined in Parkland Manitoba?

Koons, David N.; Rotella, Jay J.

doi:10.22621/cfn.v117i4.827

Cited by 18 publications

(38 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, at the Erickson breeding site, Koons and Rotella (2003) reported estimates of nest success (11%) and duckling survival (20%) during 1999-2000 to be low and similar to rates recorded for recent studies in boreal forest areas (Fournier and Hines 2001;Brook 2002;Corcoran et al 2007;Martin 2007). In southern Saskatchewan, in 1999-2000, Brook (2002 reported lower nest success (3%) and duckling survival (38% Dawson and Clark 1996) than at Yellowknife (14% and 61%, respectively).…”

Section: Introductionsupporting

confidence: 82%

“…In southern Saskatchewan, in 1999-2000, Brook (2002 reported lower nest success (3%) and duckling survival (38% Dawson and Clark 1996) than at Yellowknife (14% and 61%, respectively). As well, Koons and Rotella's (2003) nest success and duckling survival estimates at Erickson were much lower than those recorded there before the continental population decline (31% and 68%, respectively; Afton 1984), and their female breeding season survival estimate (73%) was lower than that reported for any northern-latitude breeding duck. In addition, clutch initiation date, which is often negatively associated with reproductive success (Dawson and Clark 2000;Esler et al 2001;Blums et al 2002;Brook 2002) was later than historical estimates: 24 June versus 15 June (Koons and Rotella 2003).…”

Section: Introductionmentioning

confidence: 69%

“…For boreal breeding scaup, historical nutrient reserve data are sparse (body mass only; Trauger 1971) but lipid reserves of boreal females measured during [2003][2004] in northern Alberta and the Northwest Territories were much lower than historical values reported for females in northwestern Minnesota in 1986-1988and southwestern Manitoba in 1977-1980(Anteau and Afton 2004, 2009a; but see DeVink et al 2008c). Furthermore, recent studies have reported that some reproductive parameters, such as nest success, female survival, duckling and brood survival, and breeding probability, were low in boreal and parkland breeding sites, at rates that would be consistent with the SCH (Fournier and Hines 2001;Brook 2002;Koons and Rotella 2003;Corcoran et al 2007;Martin et al 2009). Afton and Anderson (2001) and Anteau and Afton (2009a) speculated that reduced food resources at nonbreeding areas would affect body condition and, hence, recruitment of northern boreal breeders more than southern prairie-parkland breeders because of the shorter time between arrival and egg-laying in the north.…”

Section: Introductionmentioning

confidence: 84%

“…Because, at Erickson, the total number of scaup breeding pairs has declined from the early period; lower reproductive rates have been reported recently; and body condition of scaup females on arrival in spring may be lower than in the past, I predicted that recent-period reproductive rates would be lower than comparable early-period estimates. I predicted that my current estimates of productivity and duckling survival would be lower than those recorded in the early period on the basis of Koons and Rotella's (2003) findings. I also expected mean Ia and IIa brood sizes to be smaller mainly because of lower duckling survival.…”

Section: Introductionmentioning

confidence: 93%

“…Field studies conducted in parkland habitat during the scaup population decline have been of short duration, e.g., 2 years (Brook 2002;Koons and Rotella 2003), and, thus, given annual variation in environmental conditions, are of limited value in determining how reproductive rates vary over time or in understanding factors affecting the rates. Accordingly, to provide -decline, 1970-1972 (the early period) data from previous research (Hammell, unpublished data, 1973).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Reproductive Rates in Lesser Scaup (<i>Aythya affinis</i>) in Southwestern Manitoba: Another Look at the Data

Hammell¹

2016

Can Field Nat

View full text Add to dashboard Cite

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.

show abstract

Section: Introductionsupporting

confidence: 82%

Section: Introductionmentioning

confidence: 69%

Section: Introductionmentioning

confidence: 84%

Section: Introductionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Reproductive Rates in Lesser Scaup (<i>Aythya affinis</i>) in Southwestern Manitoba: Another Look at the Data

Hammell¹

2016

Can Field Nat

View full text Add to dashboard Cite

show abstract

Understanding the demographic drivers of realized population growth rates

Koons

Arnold

Schaub

2017

Ecological Applications

Self Cite

133

View full text Add to dashboard Cite

Identifying the demographic parameters (e.g., reproduction, survival, dispersal) that most influence population dynamics can increase conservation effectiveness and enhance ecological understanding. Life table response experiments (LTRE) aim to decompose the effects of change in parameters on past demographic outcomes (e.g., population growth rates). But the vast majority of LTREs and other retrospective population analyses have focused on decomposing asymptotic population growth rates, which do not account for the dynamic interplay between population structure and vital rates that shape realized population growth rates (λt=Nt+1/Nt) in time-varying environments. We provide an empirical means to overcome these shortcomings by merging recently developed "transient life-table response experiments" with integrated population models (IPMs). IPMs allow for the estimation of latent population structure and other demographic parameters that are required for transient LTRE analysis, and Bayesian versions additionally allow for complete error propagation from the estimation of demographic parameters to derivations of realized population growth rates and perturbation analyses of growth rates. By integrating available monitoring data for Lesser Scaup over 60 yr, and conducting transient LTREs on IPM estimates, we found that the contribution of juvenile female survival to long-term variation in realized population growth rates was 1.6 and 3.7 times larger than that of adult female survival and fecundity, respectively. But a persistent long-term decline in fecundity explained 92% of the decline in abundance between 1983 and 2006. In contrast, an improvement in adult female survival drove the modest recovery in Lesser Scaup abundance since 2006, indicating that the most important demographic drivers of Lesser Scaup population dynamics are temporally dynamic. In addition to resolving uncertainty about Lesser Scaup population dynamics, the merger of IPMs with transient LTREs will strengthen our understanding of demography for many species as we aim to conserve biodiversity during an era of non-stationary global change.

show abstract

Temporal variation in survival and recovery rates of lesser scaup

Arnold¹,

Afton²,

Anteau

et al. 2016

Jour. Wild. Mgmt.

Self Cite

View full text Add to dashboard Cite

Management of lesser scaup (Aythya affinis) has been hindered by access to reliable data on population trajectories and vital rates. We conducted a Bayesian analysis of historical bandrecovery data throughout North America to estimate annual survival and recovery rates for juvenile and adult male and female lesser scaup to determine if increasing harvest or declining survival rates have contributed to population changes and to determine if harvest has been primarily additive or compensatory. Annual recovery rates were low, ranging from 1% to 4% for adults and 2% to 10% for juveniles during most years, with trend models indicating that recovery rates have declined through time for all age-sex classes. Annual survival (mid-Aug to mid-Aug) averaged 0.402 (ŝ 0.043) for juvenile males, 0.416 (ŝ 0.067) for juvenile females, 0.689 (ŝ 0.109) for adult males, and 0.602 (ŝ 0.115) for adult females, whereŝ represents an estimate of annual process variation in each survival rate. Annual survival rates exhibited no evidence of long-term declines or negative correlations with annual recovery rates (i.e., an index of harvest intensity) for any age-sex class, suggesting that declining fecundity was the most likely explanation for population declines during . We conclude that hunting mortality played a minor role in affecting population dynamics of lesser scaup and waterfowl managers could take a less cautious approach in managing harvest, especially if recruiting or maintaining waterfowl hunters are viewed as important management objectives. Ó 2016 The Wildlife Society.

show abstract

Have Lesser Scaup, <em>Aythya affinis</em>, Reproductive Rates Declined in Parkland Manitoba?

Cited by 18 publications

References 34 publications

Reproductive Rates in Lesser Scaup (<i>Aythya affinis</i>) in Southwestern Manitoba: Another Look at the Data

Reproductive Rates in Lesser Scaup (<i>Aythya affinis</i>) in Southwestern Manitoba: Another Look at the Data

Understanding the demographic drivers of realized population growth rates

Temporal variation in survival and recovery rates of lesser scaup

Contact Info

Product

Resources

About