*3.3. Overall Change in Species Numbers*

In total, 165 individual species were represented in the bird records used. Of these, 23 species were recorded in 1998 only and 19 in 2018 only (Table A4). All sites showed a change in species numbers between 1998 and 2018; however, when all sites were included, there was no significant change in total species numbers (F = 1.1909, *p* = 0.3999 and F = 1.9395, *p* = 0.1707, respectively).

Focussing on those sites where urbanisation had increased or greenspace had decreased over the 20-year period, changes in species numbers were more distinctive. Although sites are listed numerically, this is for brevity, and they are not necessarily the same location.

Where urbanisation had increased, of the nine sites analysed, five sites showed an increase in overall species numbers with four of these increases found to be statistically significant (*p* < 0.05). Examination of sites where species numbers decreased found two where the decrease was significant and two where there was no statistical significance (Table 1).

**Table 1.** Results of paired *t*-test for difference in the overall number of bird species per site between 1998 and 2018 in areas where urbanisation has increased (df = 8).


In sites where there was a decrease in greenspace, the majority (10 out of 15) displayed an increase in species numbers, but of these, only three were found to be significant. The remaining five sites where a decrease in species was recorded again found three with statistical significance (Table 2).

**Table 2.** Results of paired *t*-test for difference in the overall number of bird species per site between 1998 and 2018 in areas where greenspace has decreased (df = 14).


*3.4. Changes to Species Numbers with Regard to Primary Food Sources*

Species for each site were categorised by their primary food source, and changes in numbers initially were record as either an increase, decrease or no change for each food source.

In areas where urbanisation had increased, site 6 (increase in urbanisation of 5.8%) showed an increase in every species type, whereas site 4, which had the highest increase in urbanisation of any site (58.2%), displayed a decrease in almost every species type bar one, in which there was no change (Table 3).


**Table 3.** Change in species numbers across sites where urbanisation has increased; I = increase, D = decrease and NC = no change.

Subsequent analysis found that there was no significant change in species numbers by primary food source overall (Table 4).

**Table 4.** Change in species numbers across sites where greenspace has decreased; I = increase, D = decrease and NC = no change.


When investigating those sites where greenspace had decreased, one site (7) showed an increase in every species type despite having a greater reduction in greenspace (14.2%) than either site 6 (13.4%) or site 8 (5.3%), both of which showed a reduction in every species type except those that feed primarily on vegetation (Table 4).

Unlike those sites where urbanisation had increased, analysis of changes in species numbers in the sites where greenspace had decreased found a significant change in those species whose primary food source was insects (*p* < 0.05). Some change was noted for raptors too, but this was not quite statistically significant (*p* = 0.06) (Table 5).

**Table 5.** Results of paired *t*-test for difference in the number of bird species by primary food source between 1998 and 2018 in areas where greenspace has decreased (df = 14).

