Model 1

model
{
  temp.bar <- mean(temp[])
  for (i in 1:N) {
       pres[i] ~ dnorm( mu[i], tau)
       mu[i] <- alpha + beta * (temp[i] - temp.bar)
       logpres[i] ~ dnorm(0, 0.001)
  }
  sigma <- 1/sqrt(tau)
  alpha ~ dnorm(0, 1.0E-6)
  beta ~ dnorm(0, 1.0E-6)
  tau  ~ dgamma(0.001, 0.001)
}

list(N=31)

inits
list(alpha = 0, beta = 0, tau = 1)