Figure 4. Relationship between responses and population trends.Panel (a) shows the mean population trend (±SEM) for species with
different combinations of responses in phenology and NRB. The pgsl model
b) indicated that a range shift had a significant positive effect on the
population trend (Est.= 0.37; t=2.15; p<0.05). Panel (b) shows
the mean population trend (±SEM) for species with different
hypothesis-wise responses (dark grey= hypothesis 0 ̵̶- the species neither
shift NRB nor phenology; dark blue= hypothesis 1 ̵̶- the species shifts
either NRB or phenology; light blue= hypothesis 2 ̵̶- the species shifts
both NRB and phenology). Species that responded according to Hypothesis
2 showed the strongest population trends (Est.= 0.55; t=3.08;
p<0.01).
Table 1. Conversion of phenology and NRB estimates into
categorical response groups. a) The slope coefficients from the
phenological analyses and NRB shift estimates were used to convert
continuous responses into categorical response groups. b) To enable
tests of our hypotheses, we further combined these phenology and NRB
response groups into 1) a four-level category describing combined
response groups (RG) and 2) a three-level category describing
hypothesis-wise responses (Hypotheses 0, 1, or 2), both corresponding to
the potential combined responses shown in Fig. 1b.