Equation 4: Allocate breeding females to Source habitat (B.fc)

This function outputs B.fc, the number of females that acquire high quality "source" (._c) habitat during the breeding season

eq04_Bfc(W2, K.bc)

Arguments

W2	Population vector produced after winter and northward migration survival.
K.bc	carrying capacity of breeding ground (.k_) source (._c) habitat

Value

B.fc Total number of females (f) allocated to the source (c) habitat

Details

This function compares total female population size after migration (W2.fg + W2.fp) to K.bc the source carrying capacity; if the total population of females is less than the carrying capacity (eg, code(W2.fg + W2.fp) < K.bc), all females acquire habitat in the source. Therefore when the population is small all females are allocated to source habitat regardless of where they wintered.

If W2.fg + W2.fp > K.bc, then the source habitat gets filled up completely. Any additinal females will be allocated to the sink (._k) habitat in a subsequent step using a different allocation equation.

Note that this allocation process returns just a scalar (single number). The origin of the the birds isn't tracked at this step.

The output of this function is used in equation 17.

References

Runge, MC and PP Marra. 2004. Modeling seasonal interactions in the population dynamics of migratory birds. In Greenberg, R and PP Marra, eds. Birds of two worlds. Johns Hopkins University Press, Baltimore.

Examples

# Set parameters:
## Create named population W2 vector using the eq01buildW0vect()
## 100 females originating from good winter habitat
## 10 females originating from poor winter habitat
W2 <- eq01buildW0vect(100, 10, 100, 10)

W2
#>  mg  mp  fg  fp 
#> 100  10 100  10 

#Breeding habitat carrying capacity
K.bc.110 <- 110
K.bc.100 <- 100
K.bc.10  <- 10

# The maximum number of birds that can be allocated to source habitat
# is the carrying capacity.
# When K.bc is 110, all 110 females are allocated to source
## No birds will end up in sink in subsequent steps
eq04_Bfc(W2, K.bc.110)
#> [1] 110

# If K.bc is 100, 100 birds will be allocated to source.
## The 10 remaining will be shunted to sink in a subsequent step.
eq04_Bfc(W2, K.bc.100)
#> [1] 100

# If K.bc is 10, only 10 birds will be allocated to source.
## The 100 remaining, which are a mix of birds from good and poor winter habitat
## will be allocated to sink habitat in a subsequent step.
eq04_Bfc(W2, K.bc.10)
#> [1] 10

# If the number of birds is less than K.bc, then all will be allocated to source.
W2 <- eq01buildW0vect(50, 10, 50, 10) # 60 total birds
eq04_Bfc(W2, K.bc.110)                # All 60 allocated to source
#> fg 
#> 60