<p>Dalmatian Pelican (<i>Pelecanus crispus</i>) and Great White Pelican (<i>Pelecanus onocrotalus</i>) are the only members of the Pelecanidae family that spend winter at the Anzali international wetland in northern Iran. The main purpose of this study was to compare the wintering population trends of Great White Pelican and Dalmatian Pelican over a 15-year period (2007–2021) regarding climate factors at the Anzali wetland. The results of the study showed that the temperature parameters had the highest impact on the two Pelican species’ wintering populations. According to the canonical correlation analysis (CCA), a significantly high synchrony was shown between the first canonical variate pair and the Dalmatian Pelican population (R² = -0.98). It indicated the leading effect of the temperature variations on the Dalmatian Pelican wintering population. On the contrary, the effect of temperature variation on the Great White Pelican wintering population was medium (R² = -0.45). Furthermore, analysis of the RTRIM model showed that the wintering population trend of the Great White Pelican in the study area was uncertain in the study period. Whereas the Dalmatian Pelican wintering population had an increasing overall trend (annually 5%) at the study period that was likely affected by the increase in temperature.</p>