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Survival

Survival and productivity

Nest survival and causes of nest loss

Like most waders, Sociable Lapwings lay on average 4 (mean of 3.8 ± 0.1) eggs in a shallow scrape on the ground and tend to nest in small colonies (range of 1-8 nests) (Watson et al 2006).

There are few robust estimates of nest survival from large enough sample sizes to allow comparison with current studies of Sociable Lapwing nesting biology. Gordienko (1991) reports a nest loss of 44% (from 26 nests) during the 1980s in Naurzum Reserve, Kazakhstan. 

More recently, in 2004, Watson et al (2006) report an overall Mayfield nest survival rate of 19.3% from 58 nests in a study area centred on the settlement of Korgalzhyn, central Kazakhstan (50° 35’ N, 70° 01’ E). Percentage survival estimates reported by Gordienko (1991) and Watson et al (2004) are not directly comparable. However, Gordienko found that 44% of nests with eggs (n = 26) failed. The Watson et al equivalent rate is 61% failure of nests found with eggs before hatch (n = 56); the difference in frequencies between the two studies is not significant (χ2 = 2.4, P = 0.12). Therefore, there appears to have been little change in nest survival between the 1980s and the present.

Monitoring of nest survival has continued in the Korgalzhyn study area of Watson et al between 2005 – 2012, with 1078 nests located, for which the outcome was determined  for 1032 (Sheldon et al in press). The overall daily nest survival rate across all nests in all years was 0.956 (95% CL: 0.952-0.959), equating to an overall nest survival rate of 28.4% across the 28-day laying and incubation period. However, survival rate varies greatly from year to year. One hypothesis currently being investigated is that nest survival rates fluctuate in a cycle with vole numbers; in years of high vole numbers, nest survival rates are higher than in years when vole numbers are low since predators have an abundant alternative source of food.

In the long-term study of Sheldon et al (in press) of 331 recorded nest failures, predation accounted for the greatest number of losses (63%) with trampling accounting for 20% of failures. Causes of nest failure varied from year to year, with a higher than expected proportion of losses to trampling in 2008 and a lower than expected proportion in 2010 and 2011. Across all study sites, nests that were trampled were significantly closer to human settlements than nests that were predated, though nests that were closer to human settlements still did better as predation rates were lower.

Data from 29 nest cameras showed that 7 were predated, 3 were trampled and one was deserted (the eggs later taken by Rooks Corvus frugilegus). Of the 7 losses to predation, the predators comprised Red Fox Vulpes vulpes (2), Souslik species Citellus fulvus and Spermophilis major (2), Long-eared Hedgehog Hemiechinus auritus (2), and Steppe Polecat Mustela eversmanni (1). The previous AEWA Sociable Lapwing International Single Species Action Plan (Tomkovich and Lebedeva 2004) noted that Rooks and/or domestic cats and dogs were key predators contributing to the decline in breeding numbers. However, no instances of predation by Rooks or cats/dogs were recorded on digital cameras, and in 5 years of intensive fieldwork, no nest loss could be attributed to these potential nest predators.

It is unlikely that the magnitude of the recent population decline can be wholly explained by low nest survival. However, attempts to manipulate grazing management (particularly sheep) in some key colonies may contribute to enhancing nest survival that may be beneficial at the population level.

Causes of nest failure by year from the core study population in central Kazakhstan (Sheldon et al in press).

Year

Predated

Trampled

Weather

Unknown

Deserted

Total

2005

24

5

0

6

3

38

2006

11

16

5

5

4

41

2007

53

14

0

10

3

80

2008

8

24

0

10

1

43

2009

51

10

0

2

2

65

2010

51

3

0

0

2

56

2011

33

2

0

3

6

44

Total

231

74

5

36

21

367

Fecundity and annual survival 

No historical data exist on chick survival from hatching through to fledging.

The long term study of Sheldon et al (in press) estimates mean annual fecundity from 0.75 to 1.55 chicks hatched per breeding female. The variation in annual fecundity was explained by the strong annual variation in nest survival rate, other factors such as first egg date, clutch size and partial clutch loss having little influence. Daily chick survival, estimated from 752 chicks ringed at the age of 5 days or less, was estimated at 0.983 (95% CL: 0.979-0.986), almost identical to that of Watson et al (2006).

Between 2005 and 2011, 1310 chicks and 132 adults (mostly females caught at the nest) were fitted with unique colour-ring combinations. Of these, 98 birds ringed as chicks (7.5%) and 35 birds ringed as adults (26.5%) were re-sighted in one or more subsequent years. Survival models (see Sheldon et al in press for details of survival analysis) show that birds ringed as chicks had annually variable first-year survival, and birds ringed as adults had constant survival in the year after ringing, after which annual survival of birds ringed as chicks and as adults shared common annual survival estimates. Post-hatching survival to the following year ranged from 0.11 (95% CL: 0.05-0.23) in 2007-2008 to 0.59 (0.23-0.88) in 2009-2010 (mean across all years: 0.27, 95% CL: 0.16-0.42). Adult annual apparent survival ranged from 0.19 (0.08-0.39) in 2010-2011 to 0.82 (0.25-0.98) in 2009-2010 (mean across all years: 0.55, 95% CL: 0.47-0.62) (Sheldon et al in press).

Estimates of population growth suggest that the Sociable Lapwing population is currently in decline. To reverse this decline changes in fecundity or first-year survival would need to more than double (+125%), whereas adult survival would need to increase by 30% (Sheldon et al in press). To reverse the downward population trend, conservation measures aimed at tackling low adult survival are required.

 

For full references, please visit the references page.

Sociable Lapwing nest survival bar chart
Sociable Lapwing annual fecundity bar chart
Typical nesting area near Aktubek village, Kazakhstan